bluuebunny/crossref_metadata_2025 huggingface dataset:
La integración económica de la cuenca amazónica
Authors: Moscoso Jorge Villacrés
Published: March 2007

Si bien es muy conocido que la integración económica latinoamericana, mejor dicho sudamericana, se inicia con la suscripción en 1961 del Tratado de Montevideo, hoy estamos contemplando que desde esa fecha se ha venido produciendo precisamente el proceso inverso, por una serie de causas y factores que no es el momento de analizar ni exponer y que están culminando con la desintegración económica de los países sudamericanos.

Sin tomar en cuenta a los países centroamericanos que iniciaron muy tempranamente el proceso de su integración exclusivamente entre ellos, sin referirse en nada al resto de sus hermanos latinoamericanos, los países sudamericanos y México emprendieron en 1961 su propia integración a base del ya mencionado Tratado de Montevideo; mas transcurridos algunos años, después de la Reunión de Presidentes en la ciudad de Bogotá en 1967, países como Venezuela, Colombia, Ecuador, Bolivia, Perú y Chile, resuelven crear una subzona particular de comercio denominada “Subandina”, la misma que de acuerdo con los postulados que sostiene está constituyéndose en un grupo antagónico, por no decir rival, de los que quedaron integrando el Tratado de Montevideo, o sea, Brasil, Uruguay, Paraguay y la Argentina, países que por su situación geográfica han sido denominados los del grupo del Atlántico.
The Antipositivist Movement in Prerevolutionary Mexico, 1892-1911
Authors: Raat William Dirk
Published: March 2007

The activities of the Liberal Union group in the election year of 1892, along with the subsequent appointment that next year of José Ives Limantour as Secretary of Treasury, marked the beginning of the rise of an influential clique of technocrats within the bureaucracy of Don Porfirio Díaz. In addition to Limantour, this group included, among others, Francisco Buhes, Justo Sierra, Rosendo Pineda, Pablo Macedo, and Miguel Macedo. The name the critics used to describe this clique was that of the “scientists” or the Científicos. This name was selected, among other reasons, to express the belief of the opposition that the members of the Científico group were imbued with the scientific and positivistic doctrines of the French philosopher and architect of positivism, Auguste Comte. With the coming of the Científicos to power the course of antipositivism was redirected, given an additional emphasis, and expanded to meet the needs of liberal and clerical critics of the regime.
Components of Political Change in Latin America
Authors: Fitzgibbon Russell H.
Published: March 2007

Mr. Tad Szulc, a highly perceptive and knowledgeable New York Times correspondent and certainly an “old Latin American hand” wrote very wisely: “One of the first rules a reporter needs to learn in Latin America is that he must never be swayed by reason or logic in trying to gauge future events. This precept should apply as well to the contemporary historian or to the foreign-policy maker observing the Latin American scene, who must realize that neither short- nor long-range predictions are possible and that in all wisdom none should be attempted. The scene is too crowded, the actors move too fast, propelled by visible and invisible forces of formidable magnitude.” Having uttered this warning, Mr. Szulc proceeded to violate it and make some sage observations about the “tomorrow” of Latin America.
APRA: An Appraisal
Authors: Clinton Richard Lee
Published: March 2007

Had the military not ousted President Fernando Belaúnde Terry and substituted their rule for constitutional processes, 1969 would have been an election year in Peru. According to Belaúnde, the probable winner of those elections would have been Víctor Raúl Haya de la Torre, the perennial candidate of the Alianza Popular Revolucionaria Americana (APRA). Therefore, to paraphrase the comment attributed to Mark Twain on arising from his sickbed and reading his obituary in the local newspaper, announcements of Apra's demise are somewhat premature.

Few political movements in Latin America have enjoyed a comparable fame, and none has matched that of theapristasin having contributed a nonpersonalistic genre to the family of Latin America political parties.
The Politicization of the Brazilian Catholic Church: The Catholic Electoral League
Authors: Williams Margaret Todaro
Published: March 2007

One of the most curious phenomena ever to be recorded in the annals of Latin American church history was a peculiarly Brazilian institution known as the Catholic Electoral League. Lofty in its ideals but confused in their practice, disclaiming political party status yet directly involving the Church in every political campaign of the day, the League functioned between 1932 and 1937 as a political pressure group under the direct auspices of the Roman Catholic Church. It operated on a more national scale than the political parties themselves, which were still basically regional.
The Mercantile Potpourri Called Panama
Authors: Greer Thomas V.
Published: March 2007

Panama is a land of trade. For four and a half centuries, it has been a funnel for exchange between Europe and the west coast of South America and between the Atlantic and the Pacific. This article examines the place of retail trade in the Panamanian economy, with an emphasis as much cultural and social as it is economic.
Cuban Refugee Children
Authors: Walsh Monsignor Bryan O.
Published: March 2007

During the past twelve years almost half a million Cubans have sought refuge in Miami. Among them were over 14,000 unaccompanied children between 6 and 18 years of age. This article tells for the first time the story of how the children's exodus began. It covers the period between the middle of November 1960, when we first became aware of the need, and 1 February 1961, when I met with the Secretary of the U.S. Department of Health, Education and Welfare to brief him on the plight of the unaccompanied children among the refugees. Two days later, President Kennedy announced a government aid program for Cuban refugees which included money for the care of unaccompanied children, “the most troubled group among the refugee population.”

About 4:30 p.m. on 26 December 1960, Pan American World Airways Flight 422 from Havana touched down at Miami International Airport. There were few passengers, if any, on that flight who did not experience a real sense of relief as they descended from the airplane. Events in Cuba were rapidly moving toward a climax and those who could were joining the increasing exodus to Miami.
Obstacles to Labor Absorption in a Developing Economy: Colombia, a Case in Point
Authors: Geithman David T. , Landers Clifford E.
Published: March 2007

Historically, for the now economically developed countries, a strong positive correlation has normally existed between rising real output and employment levels. Among today's lessdeveloped countries (LDC's) even high growth rates can, and frequently do, fail to generate a concomitant rapid rate of employment expansion. Indeed, so acute is the failure of labor absorption to grow in step with rising incomes that a recent International Labour Organization (I.L.O.) report on Colombia (1970: 47) maintains “development strategy will become very largely employment strategy.”

The unemployment problem is in part due to the rapid population growth rates and even more rapid urban growth rates experienced by most LDC's in the postwar period, and in part it stems from the nature of their development processes (International Bank for Reconstruction and Development, 1972: 35).
The Merchant Elite and the Development of Brazil: The Case of Bahia During the Empire
Authors: Ridings Eugene W.
Published: March 2007

Export-import merchants played a central role in the industrialization of Brazil. Many of the Brazilian Empire's noted entrepreneurs began as merchants, including the Barão de Mauá, perhaps the most famous of all, and the noted Bahian industrialist-philanthropist, Luís Tarquínio. Individual merchants served as cadres and furnished capital for early industrialization in both Bahia (Almeida, 1951: 14) and São Paulo (Dean, 1969: 19-33). That export-import merchants would play a prominent role in Brazilian development, particularly during the Empire, was logical. As intermediaries in an economy largely devoted to exporting and importing, merchants occupied a central position in the Empire's economic structure. Brazil's merchant elite was also a natural vehicle for modernizing influences from abroad because of its international trade connections and its cosmopolitan membership. For new enterprises, merchants were one of the few sources of capital and virtually the only source of business expertise.
The Education-Work Transition of Venezuelan University Stude
Authors: Zschock Dieter K. , Schuyler George W. , Fernandez Anibal , Raymond Duncan W.
Published: March 2007

University students in Venezuela constitute about ten percent of the corresponding age group (calculated from Universidad Central de Venezuela 1970: 19, Table 5), and leadership of the country's economic and social development is increasingly in the hands of university-trained professionals. University enrollment has quadrupled since 1958, and young professionals who have graduated over the past fifteen years already represent a majority among university graduates in Venezuela. Research on students and elites, however, in Venezuela as elsewhere in Latin America, has concentrated on their divergent political attitudes while paying scant attention to the transformation of university students into members of the elite.

This paper reports on an exploratory survey of student and elite attitudes toward higher education and professional employment in Venezuela. Our findings provide some insight on the extent to which employment of high-level manpower is influenced by modern, achievement-oriented criteria, as compared with traditional, ascriptive criteria.
Did the United States Plan an Invasion of Mexico in 1927?
Authors: Horn James J.
Published: March 2007

For many years the vague notion has circulated that the United States and Mexico were on the verge of war in 1927. Howard Cline (1965: 209) cited unspecified “Mexican sources” as purportedly revealing that Secretary of State Frank B. Kellogg and Ambassador James R. Sheffield in Mexico City were “purposely trying to provoke some Mexican act that could be used as a pretext for American intervention.” Former Mexican President Emilio Portes Gil (1964: 396) went further and insisted that American warships had actually mobilized for intervention, only to be thwarted by an “imperturbable” President Calles. These and other such assertions have never been thoroughly analyzed on the basis of available American diplomatic and military records. This article attempts to demonstrate that intervention was highly unlikely. Moreover, circumstantial evidence and logic combine to suggest that the administration of Calvin Coolidge never seriously considered such a move and that rumors of intervention were founded more upon Mexican suspicion and mistrust than upon realities in Washington.
Justice and Law in Latin America: A Cuban Example
Authors: Moreno Francisco José
Published: March 2007

The period immediately following Castro's overthrow of Batista on New Year's Day 1959 was followed by a series of revolutionary trials that attempted to weed out and punish supporters of the fallen dictatorship and “enemies of the revolution.” One of the most unusual of these political trials became a cause célèbre that called into question the general nature of law and justice in Castro's Cuba. The analysis of this case allows us to see clearly the relationship that has traditionally existed between the ideas of law and justice in Latin American culture. This study also touches incidentally upon the ever present judicial problem of defining the responsibility of soldiers for their actions during warfare.
A New Imidazole‐Containing Imidazolidinone Catalyst for Organocatalyzed Asymmetric Conjugate Addition of Nitroalkanes to Aldehydes
Authors: Hojabri Leila , Hartikka Antti , Moghaddam Firouz Matloubi , Arvidsson Per I.
Published: March 2007

Herein we report a new organocatalyst for the asymmetric Michael addition of nitroalkanes to α,β‐unsaturated aldehydes. This catalyst incorporates a basic imidazole group in addition to the secondary amine responsible for activation of the α,β‐unsaturated carbonyl compounds via iminium ion formation. The new organocatalyst is capable of catalyzing the enantioselective carbon‐carbon bond formation with a high degree of enantiocontrol providing products in enantiomeric excesses of up to 92 % and yields of up to to 91 %. These results constitute the best results so far reported for organocatalyzed Michael additions of nitroalkanes to α,β‐unsaturated aldehydes, and provide proof of principle that organocatalysts incorporating two internal basic moieties may find broad application in organocatalyzed Michael additions.
Dioxomolybdenum(VI)‐Catalyzed Reductive Cyclization of Nitroaromatics. Synthesis of Carbazoles and Indoles
Authors: Sanz Roberto , Escribano Jaime , Pedrosa María R. , Aguado Rafael , Arnáiz Francisco J.
Published: March 2007

Reductive cyclization of nitrobiphenyls and nitrostyrenes to carbazoles and indoles, respectively, is carried out by triphenylphosphine under mild conditions catalyzed by a dichlorodioxomolybdenum(VI) complex. A one‐pot procedure for the synthesis of regioselectively functionalized indoles has been developed from commercially available o‐nitrobenzaldehydes and phosphoranes.
Diarylmethanols by Catalyzed Asymmetric Aryl Transfer Reactions onto Aldehydes Using Boronic Acids as Aryl Source
Authors: Schmidt Frank , Rudolph Jens , Bolm Carsten
Published: March 2007

Using a planar‐chiral ferrocene as catalyst and combinations of functionalized aldehydes and substituted arylboronic acids as starting materials, asymmetric aryl transfer reactions give access to structurally diverse, optically active diarylmethanols in high yields and enantioselectivities.
Metal‐Free, Enantioselective Strecker Reactions Catalyzed by Chiral BINOL and TADDOL Catalysts
Authors: Rueping Magnus , Sugiono Erli , Moreth Stefan A.
Published: March 2007

An efficient, metal‐free Brønsted acid‐catalyzed, enantioselective hydrocyanation of ketoimines has been developed. This BINOL phosphate‐catalyzed Strecker reaction provides the corresponding amino nitriles, precursors of quaternary amino acids, in good isolated yields and enantioselectivities. Additionally, we demonstrate that chiral diols, such as TADDOL, are effective enantioselective catalysts for the hydrogen‐bond activation of aldimines.
Zirconium‐Catalyzed Asymmetric Carboalumination of Alkenes: ZACA–Lipase‐Catalyzed Acetylation Synergy
Authors: Huang Zhihong , Tan Ze , Novak Tibor , Zhu Gangguo , Negishi Ei‐ichi
Published: March 2007

ZACA–lipase‐catalyzed acetylation tandem reactions provide highly efficient and selective routes to either (R)‐ or (S)‐2‐methyl‐1‐alkanols, making, for the first time, the ZACA‐based asymmetric synthesis of 2‐methyl‐1‐alkanols widely applicable and satisfactory.
Enantioselective Ring Opening of Epoxides with Silicon Tetrachloride in the Presence of a Chiral Lewis Base: Mechanism Studies
Authors: Denmark Scott E. , Barsanti Paul A. , Beutner Gregory L. , Wilson Tyler W.
Published: March 2007

The enantioselective ring opening of meso‐epoxides (from both cyclic and acyclic olefins) with silicon tetrachloride under catalysis by chiral phosphoramides affords enantiomerically enriched chlorohydrins in excellent yields. Experiments designed to elucidate the mechanistic foundation and origins of enantioselectivity are described. From studies on the loading and stoichiometry of the reagent (SiCl4) and the catalyst [(R)‐1] it was established that only one chloride per SiCl4 is delivered and that the nature of reactive species does not change over the course of the reaction. Kinetic studies together with asymmetric amplification experiments have suggested that more than one catalyst molecule may be bound to SiCl4 in the stereochemistry‐determining transition structure.
Optimisation of Conditions for O‐Benzyl and N‐Benzyloxycarbonyl Protecting Group Removal using an Automated Flow Hydrogenator
Authors: Knudsen Kristian Rahbek , Holden John , Ley Steven V. , Ladlow Mark
Published: March 2007

A versatile, fully automated flow hydrogenator has been developed that is able to perform sequential flow optimisation experiments, flow library hydrogenation, or iterative scale‐up hydrogenation. The behaviour of a palladium catalyst in effecting removal of O‐benzyl and N‐benzyloxycarbonyl protecting groups has been investigated. Significant observations relating to maintaining optimal throughput are reported. A small library of peptidic derivatives has been deprotected in high yield and purity.
Chemoselective Palladium‐Catalyzed Reaction in Aqueous Media: Selectivity in the Reaction of Haloanilines with 1,1‐Dimethylallyl Alcohol
Authors: Yokoyama Yuusaku , Takagi Noriko , Hikawa Hidemasa , Kaneko Satoru , Tsubaki Natsume , Okuno Hiroaki
Published: March 2007

Palladium‐catalyzed reactions of various haloanilines with 1,1‐dimethylallyl alcohol were carried out in the presence of a hydrophilic ligand, 3,3′,3′′‐phosphinidyne tris(benzenesulfonic acid) trisodium salt (TPPTS), or a lipophilic phosphine ligand, 1,1′‐bis(diphenylphosphino)ferrocene (DPPF). The reactions proceeded chemoselectively in aqueous solvent to give C‐vinylated products under basic conditions or N‐allylated products under neutral conditions in practical yields (up to 79 %). The use of an aqueous solvent played an important role in this chemoselectivity and allowed the development of a one‐pot synthesis of 3‐methylindole. This chemoselectivity is synthetically useful because the reactive position of haloanilines can be controlled simply by changing the basicity of the reaction medium, which eliminates the need to protect the amino group during the reaction.
Synthesis of Biaryls via Palladium‐Catalyzed [2+2+2] Cocyclization of Arynes and Diynes: Application to the Synthesis of Arylnaphthalene Lignans
Authors: Sato Yoshihiro , Tamura Takayuki , Kinbara Atsushi , Mori Miwako
Published: March 2007

A novel method for construction of biaryls via palladium(0)‐catalyzed [2+2+2] cocyclization of diynes and arynes was developed. By this [2+2+2] cocyclization, various arylnaphthalene derivatives, including a sterically hindered 2,2′‐disubstituted‐1,1′‐binaphthyl, can be constructed by virtue of a variety of combinations of diynes and aryne precursors. Using this [2+2+2] cocyclization as a key step, the total syntheses of natural arylnaphthalene lignans, taiwanin C, taiwanin E, and dehydrodesoxypodophyllotoxin were achieved.
Characterization of Dimeric and Tetrameric μ‐Hydroxide Ytterbium(III) Binaphtholate Complexes
Authors: Wooten Alfred J. , Salvi Luca , Carroll Patrick J. , Walsh Patrick J.
Published: March 2007

Shibasaki’s heterobimetallic Lewis acids, M3(THF)n(BINOLate)3Ln (M=Li, Na, K and Ln=lanthanide), are an exceptionally useful class of asymmetric catalysts that exhibit high levels of enantioselectivity across a wide range of reactions. In many instances, it is necessary to add water (and base) to achieve maximum enantioselectivity. We have investigated the reaction of water with M3(THF)n(BINOLate)3Yb (M=Li, K) complexes and observed formation of a novel hydroxide‐bridged dimer (M=Li) and tetramer (M=K). These compounds have been characterized, including X‐ray structure analysis. Under anhydrous conditions, only 6‐coordinate monomeric Li3(THF)n(BINOLate)3Yb and K3(THF)n(BINOLate)3Yb complexes were isolated and characterized by X‐ray crystallography. Isolation of the dimer Li4(THF)7(BINOLate)4Yb2(μ‐OH)2 and tetramer K4(THF)9(BINOLate)6Yb4(μ3‐OH)4 indicates that added water can react with this important class of bifunctional catalyst to give new products.
Averaging theory for diesel particulate filter regeneration
Authors: Zheng Haishan , Keith Jason M.
Published: March 2007

Axial thermal gradients play a key role in monolithic diesel particulate filters. For complete particulate regeneration, the ignition location must be near the leading edge of the diesel particulate filter. A new reduced model in terms of the capacitance‐weighted and mixing cup average temperature is formulated here using the Liapunov–Schmidt reduction technique to describe the ignition behavior and account for the axial variation. The major advantage of the reduced model is that one can neglect the details of the fine scale dynamics and focus on the large scale dynamics. This new, reduced model has the ability to accurately predict two important ignition characteristics: ignition time and ignition length. Based on the reduced model results, it is shown that the thermal dispersion [a coupling of transverse diffusion (short‐scale) and axial convection (long‐scale)] plays a dominant role on ignition. © 2007 American Institute of Chemical Engineers AIChE J, 2007
Mechanistic approach to enhancement of the yield of a sonochemical reaction
Authors: Sivasankar Thirugnanasambandam , Paunikar Ashwin W. , Moholkar Vijayanand S.
Published: March 2007

In this study, a mechanistic approach has been taken to enhance yield of a sonochemical reaction. Formation of highly reactive free radicals due to the transient collapse of cavitation bubbles is the primary mechanism of a sonochemical reaction. A physical (reduction in dissolved gas concentration) and a chemical (increasing the reactant concentration) technique is used for enhancing yield of a sonochemical reaction using those techniques, which influence the phenomenon of radical formation by the cavitation bubbles. A bubble dynamics model is used for explaining the sonochemical phenomena. In a degassed medium, the ultrasound wave undergoes lesser attenuation; moreover, equilibrium size of a bubble shrinks due to rectified diffusion. Because of this, a bubble undergoes more violent collapse, resulting in greater production of radicals that give higher yield. On the other hand, increasing the initial reactant concentration shows an adverse effect on the sonochemical yield. This is ascribed to reduction in water vapor flux in the bubble due to reduction of vapor pressure of the medium. This study, therefore, demonstrates as how macroscopic manifestation (the sonochemical yield) of the microscopic phenomena (transient collapse of cavitation bubble) is a complicated function of several physical processes. The results of this study shed light on the complex and multifaceted physical mechanism of a sonochemical reaction, which may be useful in maximization of yield of other sonochemical systems. © 2007 American Institute of Chemical Engineers AIChE J, 2007
Response to novel food and the role of social influences in common marmosets (Callithrix jacchus) and Goeldi's monkeys (Callimico goeldii)
Authors: Addessi Elsa , Chiarotti Flavia , Visalberghi Elisabetta , Anzenberger Gustl
Published: March 2007

Neophobia, defined as showing caution toward novel features of the environment, is widespread in birds and mammals; it can be affected by ecology, early experience, and social context. In this study, we aimed to (i) investigate the response to novel food in adult common marmosets and Goeldi's monkeys and (ii) assess the role of social influences. We used an experimental paradigm employed previously with capuchin monkeys and children, in which a subject (observer) was presented with a novel food under three conditions: (i)Presence: group members did not have food; (ii)Different color: group members received familiar food whose color differed from that of the observer's novel food; (iii)Same color: group members received familiar food of the same color as the observer's novel food. Although most common marmosets tasted and/or ate the novel food, none of the Goeldi's monkeys ate it and only two sampled it. Differences in home range size and early social experience might explain the divergent behavior of the two species. Observers of both species similarly attended to group members and their visual attention increased with the number of group members eating, especially when the observer's and group members' foods were perceptually similar. However, we observed social influences on explorative behavior in Goeldi's monkeys but not on explorative or eating behavior in common marmosets. This result might be explained by the different pattern of response to novel food observed in the two species. Moreover, social influences on Goeldi's monkeys' behavior were nonspecific, i.e. they were not based on an appreciation that the food is safebecauseeaten by group members. Am. J. Primatol. 69:1210–1222, 2007. © 2007 Wiley‐Liss, Inc.
Huntington's disease–like 2 is associated with CUG repeat‐containing RNA foci
Authors: Rudnicki Dobrila D. , Holmes Susan E. , Lin Mark W. , Thornton Charles A. , Ross Christopher A. , Margolis Russell L.
Published: March 2007

Objective

Huntington's disease–like 2 (HDL2) is caused by a CAG/CTG expansion mutation on chromosome 16q24.3. The repeat falls, in the CTG orientation, within a variably spliced exon of junctophilin‐3 (JPH3). The existence of a JPH3 splice variant with the CTG repeat in 3′ untranslated region suggested that transcripts containing an expanded CUG repeat could play a role in the pathogenesis of HDL2, similar to the proposed pathogenic role of expanded CUG repeats in myotonic dystrophy type 1 (DM1). The goal of this study, therefore, was to test the plausibility of an RNA gain‐of‐function component in the pathogenesis of HDL2.

Methods

The presence and composition of RNA foci in frontal cortex from HDL2, Huntington's disease, DM1, and control brains were investigated by in situ hybridization and immunohistochemistry. An untranslatable JPH3 transcript containing either a normal or an expanded CUG repeat was engineered and expressed in human embryonic kidney 293 and HT22 cells to further test the toxic RNA hypothesis. The formation of RNA foci and the extent of cell death were quantified.

Results

RNA foci resembling DM1 foci were detected in neurons in HDL2 cortex and other brain regions. Similar to DM1, the foci colocalize with muscleblind‐like protein 1, and nuclear muscleblind‐like protein 1 in HDL2 cortical neurons is decreased relative to controls. In cell experiments, expression of a JPH3 transcript with an expanded CUG repeat resulted in the formation of RNA foci that colocalized with muscleblind‐like protein 1 and in cell toxicity.

Interpretation

These results imply that RNA toxicity may contribute to the pathogenesis of HDL2. Ann Neurol 2007;61:272–282
Lithium Diisopropylamide: Solution Kinetics and Implications for Organic Synthesis
Authors: Collum David B. , McNeil Anne J. , Ramirez Antonio
Published: March 2007

Lithium diisopropylamide (LDA) is a prominent reagent used in organic synthesis. In this Review, rate studies of LDA‐mediated reactions are placed in the broader context of organic synthesis in three distinct segments. The first section provides a tutorial on solution kinetics, emphasizing the characteristic rate behavior caused by dominant solvation and aggregation effects. The second section summarizes substrate‐ and solvent‐dependent mechanisms that reveal basic principles of solvation and aggregation. The final section suggests how an understanding of mechanism might be combined with empirical methods to optimize yields, rates, and selectivities of organolithium reactions and applied to organic synthesis.
Chemiluminescent picture of diphenyleneiodonium‐inhibited NADPH oxidase: a bimodal process and its logistic–exponential model‐based description
Authors: Kochel Bonawentura , Vocks Andreas , Arnhold Jürgen
Published: March 2007

A chemiluminescence (CL) study of diphenyleneiodonium‐inhibited NADPH oxidase was performed on a cellular system containing neutrophils stimulated by phorbol myristate acetate, indicating a complex bimodal structure of CL processes corresponding to different stages of the inhibition. The complex structure of these processes was described by a superposition of two logistic–exponential (LE) models, characterizing these processes as bimodal ones. To determine the mechanistic foundation of the LE model‐described processes, a generalized form of the second‐order dynamic system of CL reactions, the solution to which corresponds to the LE model, was constructed. The diphenyleneiodonium effects on neutrophil NADPH oxidase were separated from the total bimodal CL of the whole measurement system by the use of difference CL processes. These difference processes were also found to be bimodal; thus, inhibitor‐induced reduction of CL could be described by a second‐order dynamic system. The rate constants and initial concentrations in this dynamic system were determined by the least squares method applied to numerical solutions approximating the difference processes. Using interrelations between the parameters of the dynamic system, cooperative effects in the inhibitor reactions with NADPH oxidase were found and described quantitatively. Other evidences of cooperativity were obtained from integral characteristics of the CL reduction process, i.e. dose–response and progress curves, determined by numerical integration of the LE models constituting the superposition. On this basis, it was also possible to detect a specific binding of the inhibitor to the enzyme. Finally, putative reaction mechanisms suggested by the model obtained were considered and compared with those known at present. Copyright © 2007 John Wiley & Sons, Ltd.
Modification of β‐lactoglobulin by microbial transglutaminase under high hydrostatic pressure: Localization of reactive glutamine residues
Authors: Partschefeld Claudia , Richter Sandy , Schwarzenbolz Uwe , Henle Thomas
Published: March 2007

Microbial transglutaminase (mTG) mediated modification of bovine β‐lactoglobulin (bLG) at ambient and high hydrostatic pressure was investigated in order to characterize preferred sites of the crosslinking reaction by identifying reactive glutamine residues. bLG was labeled with triglycine (GGG) by incubation with mTG at ambient pressure or at 400 MPa, respectively, and was subjected to an enzymatic digestion with trypsin. The resulting peptides were separated and those containing glutamine residues modified with GGG were unambiguously identified using RP‐HPLC with ESI‐TOF‐MS. For bLG treated with mTG at ambient pressure for 1 h at 40°C, no labeling was observed, thus confirming that the native protein is no substrate for mTG. After incubation of the protein with mTG at 400 MPa for 1 h at 40°C, four out of nine glutamine residues, namely at positions 5, 13, 35, and 59 were identified as accessible for the mTG catalyzed reaction, indicating partial unfolding of bLG under pressure and exposure of previously unaccesible glutamine residues. Thus, only a limited number of glutamine residues were substrates for mTG, which points to a pronounced substrate specificity of mTG toward individual glutamine residues within a protein.
Mapping of the epitope of monoclonal antibody 2B4 to the proline‐rich region of human Huntingtin, a region critical for aggregation and toxicity
Authors: Dehay Benjamin , Weber Chantal , Trottier Yvon , Bertolotti Anne
Published: March 2007

Huntington's disease is a neurodegenerative disease caused by a polyglutamine (polyQ) expansion in Huntingtin, which provokes aggregation of a proteolytic amino‐terminal fragment of the affected protein encompassing the polyQ expansion. Accumulation of mutant Huntingtin somehow triggers cellular dysfunction and leads to a progressive degeneration of striatal neurons. Despite considerable efforts, the function of Huntingtin as well as the precise molecular mechanisms by which the expanded polyQ elicits cellular dysfunction remain unclear. In addition, no treatment is available to prevent, cure, or even slow down the progression of this devastating disorder. Antibodies are valuable tools to understand protein function and disease mechanisms. Here, we have identified the epitope recognized by the mAb 2B4, a broadly used antibody generated against the amino‐terminal region of Huntingtin, which detects both aggregated and soluble Huntingtin. The 2B4 antibody specifically recognizes amino acids 50–64 of human Huntingtin but not the murine homologous region. Furthermore, the 2B4 epitope resides within the proline‐rich region of Huntingtin, which is critical for polyQ aggregation and toxicity. These properties suggest that the 2B4 antibody might be useful in antibody‐based therapeutic strategies.
Unique side chain conformation of a leu residue in a triple‐helical structure
Authors: Okuyama Kenji , Narita Hirotaka , Kawaguchi Tatsuya , Noguchi Keiichi , Tanaka Yuji , Nishino Norikazu
Published: March 2007

Single crystal structures of host‐guest peptides, (Pro‐Hyp‐Gly)4‐Leu‐Hyp‐Gly‐(Pro‐Hyp‐Gly)5 (LOG1) and (Pro‐Hyp‐Gly)4‐ (Leu‐Hyp‐Gly)2‐(Pro‐Hyp‐Gly)4 (LOG2), have been determined at 1.6 Å and 1.4 Å resolution, respectively. In these crystals, the side chain conformations of the Leu residues were (+)gauche‐trans. This conformational preference for the Leu side chain in the Leu‐Hyp‐Gly sequence was explained by stereochemical considerations together with statistical analysis of Protein Data Bank data. In the (+)gauche‐trans conformation, the Leu side chain can protrude along the radial direction of the rod‐like triple‐helical molecule. One strong hydrophobic interaction of the Leu residue was observed between adjacent molecules in the LOG2 crystal. Because the Leu‐Hyp‐Gly sequence is one of the most frequently occurring triplets in Type I collagen, this strong hydrophobic interaction can be expected in a fibrillar structure of native collagen. All the Leu residues in the asymmetric unit of the LOG1 and LOG2 crystals had water molecules hydrogen bonded to their NH. These water molecules made three additional hydrogen bonds with the Hyp OH, the Gly OC, and a water molecule in the second hydration shell, forming a tetrahedral coordination of hydrogen bonds, which allows a smaller mean‐square displacement factor of this water oxygen atom than those of other water molecules. These hydrogen bonds stabilize the molecular and packing structures by forming one OC(Gly)‐‐‐W‐‐‐OH(Hyp) intra‐molecular linkage and two NH(Leu)‐‐‐W‐‐‐OC(Gly) and NH(Leu)‐‐‐W‐‐‐OH(Hyp) inter‐molecular linkages. © 2007 Wiley Periodicals, Inc. Biopolymers 86: 212–221, 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
Bis(phosphinimino)methanide Rare Earth Amides: Synthesis, Structure, and Catalysis of Hydroamination/Cyclization, Hydrosilylation, and Sequential Hydroamination/Hydrosilylation
Authors: Rastätter Marcus , Zulys Agustino , Roesky Peter W.
Published: March 2007

A series of yttrium and lanthanide amido complexes [Ln{N(SiHMe2)2}2{CH(PPh2NSiMe3)2}] (Ln=Y, La, Sm, Ho, Lu) were synthesized by three different pathways. The title compounds can be obtained either from [Ln{N(SiHMe2)2}3(thf)2] and [CH2(PPh2NSiMe3)2] or from KN(SiHMe2)2 and [Ln{CH(PPh2NSiMe3)2}Cl2]2, while in a third approach the lanthanum compound was synthesized in a one‐pot reaction starting from K{CH(PPh2NSiMe3)2}, LaCl3, and KN(SiHMe2)2. All the complexes have been characterized by single‐crystal X‐ray diffraction. The new complexes, [Ln{N(SiHMe2)2}2{CH(PPh2NSiMe3)2}], were used as catalysts for hydroamination/cyclization and hydrosilylation reactions. A clear dependence of the reaction rate on the ionic radius of the center metal was observed, showing the lanthanum compound to be the most active one in both reactions. Furthermore, a combination of both reactions—a sequential hydroamination/hydrosilylation reaction—was also investigated.
Three‐Dimensional Lanthanide(III)–Copper(II) Compounds Based on an Unsymmetrical 2‐Pyridylphosphonate Ligand: An Experimental and Theoretical Study
Authors: Ma Yun‐Sheng , Li Hui , Wang Jun‐Jie , Bao Song‐Song , Cao Rong , Li Yi‐Zhi , Ma Jing , Zheng Li‐Min
Published: March 2007

Based on an unsymmetrical 2‐pyridylphosphonate ligand, two types of LnIII–CuII compounds with three‐dimensional structures were obtained under hydrothermal conditions, namely, Ln2Cu3(C5H4NPO3)6⋅4 H2O (1⋅Ln; Ln=La, Ce, Pr, Nd) and Ln2Cu3(C5H4NPO3)6 (2⋅Ln; Ln=Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho). Compounds 1⋅Ln are isostructural and crystallize in chiral cubic space group I213. In these structures, each Ln ion is nine‐coordinate and has a tricapped triprismatic geometry, while each Cu center is six‐coordinate with an octahedral environment. The {LnO9} polyhedra and {CuN2O4} octahedra are connected by edge sharing to form an inorganic open framework structure with a 3‐connected 10‐gon (10,3) topology in which the Ln and Cu atoms are alternately linked by the phosphonate oxygen atoms. Compounds 2⋅Ln are isostructural and crystallize in trigonal space group R$\bar 3$. In these structures, the {LnO6} octahedra are triply bridged by the {CPO3} tetrahedra by corner sharing to form an infinite chain along the c axis. Each chain is connected to its six equivalents through corner sharing of {CPO3} tetrahedra and {CuN2O2} planes to form a three‐dimensional framework structure in which the Ln and Cu atoms are linked purely by O‐P‐O units. The formation of these two types of structures is rationalized by quantum chemical calculations, which showed that both the lanthanide contraction and the electron configuration of CuII play important roles. When CuII was replaced by ZnII, only the first type of compounds resulted. The magnetic properties of complexes 1⋅Ln and 2⋅Ln were investigated. The nature of LnIII–CuII (Ln=Ce, Pr, Nd) interactions is illustrated by comparison with their LnIII–ZnII analogues.
Left bundle‐branch block—pathophysiology, prognosis, and clinical management
Authors: Francia Pietro , Balla Cristina , Paneni Francesco , Volpe Massimo
Published: March 2007

Given its broad use as a screening tool, the electrocardiogram (ECG) has largely become one of the most common diagnostic tests performed in routine clinical practice. As a result, the finding of left bundle‐branch block (LBBB) in the absence of a well‐defined clinical setting has become relatively frequent and raises questions and often concerns. While in the absence of clinically detectable heart disease LBBB does not necessarily imply poor outcomes, physicians should be aware of the role of LBBB in stratifying risk of cardiovascular events and death in subjects with both ischemic and nonischemic heart disease. This paper reviews historical landmarks, pathophysiologic features, prognostic implications, and clinical management of LBBB in apparently healthy subjects and those with heart disease. Copyright © 2007 Wiley Periodicals, Inc.
Fibroblast growth factor–hedgehog interdependence during retina regeneration
Authors: Spence Jason R. , Aycinena Juan‐Carlos , Del Rio‐Tsonis Katia
Published: March 2007

The embryonic chick is able to regenerate the retina after it has been removed. We have previously shown that proliferating stem/progenitor cells present in the ciliary body/ciliary marginal zone (CB/CMZ) of the chick eye are responsible for regeneration, which can be induced by ectopic fibroblast growth factor‐2 (FGF2) or Sonic hedgehog (Shh). Here, we reveal the mechanisms showing how FGF2 and Shh signaling are interdependent during retina regeneration. If the FGF pathway is inhibited, regeneration stimulated by Shh is inhibited. Likewise, if the Hedgehog pathway is inhibited, regeneration stimulated by FGF2 is inhibited. We examined early signaling events in the CB/CMZ and found that FGF2 or Shh induced a robust Erk phosphorylation during the early stages of retina regeneration. Shh also up‐regulated the expression of several members of the FGF signaling pathway. We show that ectopic FGF2 or Shh overexpression increased the number of phosphohistone 3 (PH3)‐positive cells in the CB/CMZ and inhibition of either pathway decreased the number of PH3‐positive cells. Additionally, both FGF and Hh signaling are required for cell survival in the CB/CMZ, whereas Hh and not FGF signaling plays a role in maintaining the identity of the retinal progenitor population in this region. Combined, our results support a model where the FGF and Hedgehog pathways work together to stimulate retina regeneration. Developmental Dynamics 236:1161–1174, 2007. © 2007 Wiley‐Liss, Inc.
ICER/CREM‐mediated transcriptional attenuation of IL‐2 and its role in suppression by regulatory T cells
Authors: Bodor Josef , Fehervari Zoltan , Diamond Betty , Sakaguchi Shimon
Published: March 2007

Here, we report that inducible cAMP early repressor/cAMP response element modulator (ICER/CREM) is induced early in CD25+CD4+ regulatory T cell (TR) assays mainly in activated Foxp3– effector T cells and this induction correlates with sharp decrease in number of IL‐2‐expressing T cells. Importantly, RNAi targeting of ICER/CREM in responder CD25–CD4+ T cells antagonizes TR‐mediated suppression. Moreover, forced expression of Foxp3 in naive CD25– T cells induces constitutive expression of ICER/CREM in T cells with a regulatory phenotype. Foxp3 facilitates expression of ICER/CREM both in Foxp3 transductants as well as CD25– responder T cells suggesting that induction of TR function in suppression assays may utilize contact‐dependent interaction. Indeed, CTLA‐4 blockade or use of B7‐deficient CD25– responder T cells prevents ICER/CREM accumulation and leads to the rescue of IL‐2 expression. Therefore, we propose that CTLA‐4 binding to B7 ligands expressed on activated ligand‐bearing Foxp3– effector T cells results in ICER/CREM‐mediated transcriptional attenuation of IL‐2. Collectively, these data suggest that Foxp3 expression in TR cells imposes suppression in contact‐dependent fashion by induction of constitutive ICER/CREM expression in activated CD25+ Foxp3– T cell effectors thus preventing them from producing IL‐2.
Mast cells play a key role in the developmentof late airway hyperresponsiveness through TNF‐αin a murine model of asthma
Authors: Kim Young‐Suk , Ko Hyun‐Mi , Kang Nam‐In , Song Chang‐Ho , Zhang Xin , Chung Woo‐Chan , Kim Jae‐Hong , Choi In‐Hak , Park Young‐Min , Kim Gi‐Young , Im Shun‐Young , Lee Hern‐Ku
Published: March 2007

We have investigated the role of TNF‐α in mast cell‐mediated late airway hyperresponsiveness (AHR) using mast cell‐deficient WBB6F1‐W/Wv (W/Wv) mice in a murine model of asthma, which exhibits a biphasic increase in AHR. TNF‐α levels in the airway and magnitude of late AHR in response to airway allergen challenge were severely impaired in W/Wv mice compared to their littermates. In addition to TNF‐α, cytosolic phospholipase A2 (cPLA2) phosphorylation and enzymatic activity in the lungs were also impaired in W/Wv mice. Either anti‐TNF‐α antibody or an inhibitor of cPLA2 abolished late AHR in congeneic +/+ mice. Intratracheal administration of TNF‐α resulted in increases in late AHR, cPLA2 phosphorylation, cPLA2 activity, and phosphorylation of mitogen‐activated protein kinases. Mast cell replacement restored airway TNF‐α level, cPLA2 phosphorylation and enzymatic activity in the lungs as well as late AHR in W/Wv mice. These data indicate that mast cells play a key role in the development of late AHR through liberation of TNF‐α.
Functional and phenotypic characterizationof tetanus toxoid‐specific human CD4+ T cellsfollowing re‐immunization
Authors: Cellerai Cristina , Harari Alexandre , Vallelian Florence , Boyman Onur , Pantaleo Giuseppe
Published: March 2007

The formation of immunological memory is a hallmark of adaptive immunity and the goal of vaccination. For CD8+ T cells, successful generation of memory cells has been linked to IL‐7 receptor alpha (IL‐7Rα) expression, suggesting a role for IL‐7 signaling, which in turn is important for preventing T cell apoptosis. We thus investigated the kinetics and changes of IL‐7Rα and anti‐apoptotic protein Bcl‐2 expression levels in tetanus toxoid (TT)‐specific CD4+ T cells at different time points prior and after TT re‐immunization of TT‐immune individuals. Prior to re‐immunization, most TT‐specific CD4+ T cells were high IL‐2 producers, CD45RA–CCR7+, IL‐7RαhighBcl‐2high cells, resembling typical long‐lived central memory cells. Already 5 days, and more importantly at the peak of the response, after TT re‐immunization, a substantial fraction of these cells secreted also IFN‐γ, down‐regulated CCR7, IL‐7Rα and Bcl‐2 and became Ki67 positive, resembling effector memory cells. In contrast, TT‐specific CD4+ T cells found 60 days or later after re‐immunization were again as baseline. Interestingly, a significant fraction of IL‐7RαhighBcl‐2high TT‐specific CD4+ T cells, i.e. the proposed memory cell precursors, remained stable at any time point upon re‐immunization. Together, these results suggest that IL‐7Rα expression levels might be a useful marker for identifying long‐lived Ag‐specific CD4+ T cells in memory T cells.
Synthesis, Crystal Structures, and Photoluminescence of a Series of Coordination Polymers with Two Homologous Functional Flexible Ligands
Authors: Zhou Hong‐Ping , Wang Peng , Hu Zhang‐Jun , Li Lin , Chen Jing‐Jin , Cui Yang , Tian Yu‐Peng , Wu Jie‐Ying , Yang Jia‐Xiang , Tao Xu‐Tang , Jiang Min‐Hua
Published: March 2007

Two functional, flexible ligands, namely 3,6‐dipyrazolyl‐9‐ethylcarbazole (L1) and 3,6‐diimidazolyl‐9‐ethylcarbazole (L2) have been synthesized and characterized and their coordination to various AgI, CdII, and CoII salts investigated. Six new complexes, 1–6, have been obtained and fully characterized by IR spectroscopy, elemental analysis, and single‐crystal X‐ray diffraction. The 2D double helix framework of the complex [CdL1I2]n (1) is formed by C–H···I hydrogen bonds, whereas the same 2D double helix framework of compound [{AgL1SO3PhCH3}2(CH3OH)(H2O)]n (2) is formed by S–O···H and C–H···O hydrogen bonds and weak π–π interactions. The coordination modes of CdII and CoII in [CdL22(NCS)2]n (3), [CoL22(NCS)2(CHCl3)2]n (4), [CdL22(NO3)2(CH3OH)2]n (5), and [CoL22(NO3)2(CH3OH)2]n (6) are the same, but in the packing diagram interlayers form a 3D network through C–H···S interactions and π–π interactions in 3, interlayers form a 3D network through S···S interactions and π–π interactions in 4, novel 3D structures are formed by interchain O···H–C hydrogen bonding and interlayer O···H–C hydrogen‐bonding and π–π interactions in 5 and 6. The structural differences between these complexes show the influence of the orientation of the coordinating group of the ligand. These results also show that the metal ion, anion, and nonbonding and π–π interactions are significant factors in controlling the structural topology of these metal‐organic supramolecular architectures. In addition, the luminescence properties of L1, 1, L2, and 3 are investigated in the solid state at room temperature. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)