bluuebunny/crossref_metadata_2025_split huggingface dataset:
CAROTENOID PIGMENTS AND THE IN VIVO SPECTRUM OF BACTERIOCHLOROPHYLL
Authors: Crounse J. , Sistrom W. R. , Nemser Suzanne 
Published: January 2008

Abstract— The isolation of a mutant, strain PM‐9, of Rhodopseudonionus spheroides with an abnormal complement of carotenoid pigments is described.PM‐9 accumulates phytoene, phytofluene, ζ‐carotene and neurosporene. Semi‐aerobic cultures form more ζ‐carotene and neurosporene relative to total carotenoids than do photo‐synthetic cultures.PM‐9 is killed on exposure to light and oxygen.By making use of the effect of oxygen on the nature of the carotenoids in PM‐9, we have shown that these pigments do not directly influence the in vivo spectrum of bacteriochlorophyll.Diphenylamine inhibits the synthesis of coloured carotenoids in Rhodopseudonionos gelatinosa but does not change the bacteriochlorophyll spectrum.
ON THE MECHANISM OF PHOTOSENSITIZING ACTION OF CHLOROPHYLL
Authors: Evstigneev V. B. 
Published: January 2008

Abstract— The paper presents ideas according to which the primary photochemical reaction of chlorophyll and its analogs can be either photooxidation or photoreduction of the pigment sensitizer depending on the reaction conditions. The factors determining the course of the process of photosensitization comprise the nature and state of the pigment and participating reagents, the nature and reaction of the medium, concentration of the oxidant and reductant, their ability to form complexes with the pigment, etc.The paper presents the results of simple kinetic investigations in which, by means of changing pH of the medium, conditions were created favouring either the primary photo‐oxidation or the primary photoreduction of the pigment‐sensitizer. These results, as well as the data of experiments on the changes in reagents' concentration show the reality of the above mentioned concepts.Considerations are presented on the possibility of photochemical interaction of two chlorophyll molecules in vivo during the photosensitization of photosynthesis.
MOLECULAR DETAILS OF PHOTOCHEMICAL TRANSFORMATIONS
Authors: ZIMMERMAN HOWARD 
Published: January 2008

Abstract— Photochemical reactions originate from electronically excited species whose structures are often susceptible to description without excessive difficulty. The factors determining the transformations which these species will most likely undergo are less certain. Our approach has been to develop suitable structures for the excited state involved and then to consider pathways requiring accessible energies. Such pathways can be found by molecular orbital and qualitative valence bond reasoning. This approach reasons that successful transformations tend to be minimum energy processes and will proceed with continuous electron redistribution. Conversely, the pathways taken in a photochemical reaction can often be used to cast light on the reactant excited state structure involved. Examples of this approach and of recent photochemical research by the author are given.RESUMENLas reacciones fotoquímicas son originadas a partir de especies electrónicamente excitadas cuyas estructuras pueden ser descriptas sin mayor dificultad para un gran número de càsos. Sin embargo los factores que determinan este tipo de transformación no están claros. En este trabajo se han tratado de desarrollar estructuras apropiadas para los estados excitados involucrados en el proceso para luego proponer caminos que requieran cantidades de energía accesibles. Estos caminos pueden ser encontrados a partir de razona‐mientos que involucran orbitales moleculares y nociones cualitativas de Valencia. Este tipo de razonamiento establece que transformaciones sucesivas tienden a ser procesos de mínima energía, que prosequirán con redistribuciones electrónicas continuas. Por otra parte, los caminos tornados en una reacción fotoquímica pueden usarse a menudo para esclarecer la estructura del estado excitado del reactante empleado. Se dan ejemplos de lo expuesto y de una reciente investigación del autor.
CORRELATION OF ORBITAL CLASSIFICATION OF MOLECULAR ELECTRONIC TRANSITIONS WITH TRANSITION MECHANISM: THE AROMATIC AMINES*
Authors: KASHA MICHAEL , RAWLS H. RALPH 
Published: January 2008

ResumenEl par de electrones aislados del heteroátomo tiene dos orbitales; uno de no unión, orbital ‐n, el cual es del tipo s̀y es ortogonal con respecto a los orbitales de los electrones; y otro de union orbital l, que está relacionado con los electrones π, a un grado en que depende del ángulo de torsión entre el eje del orbital l y el orbital 2pπ del anillo aromático vecino. La excitación de electrones a partir de los orbitales n ó l a orbitales de anti‐unión del tipo π es tratada como una transición de transferencia de carga int amolecular. Se desarrolla un detallado análisis teórico del elemento matricial órbita‐spin para una mezcla singlete‐triplete de las promociones 1 a π en anilinas, usando dos centros integrados. El momento de la transición singlete triplete depende del ángulo de torsión entre el eje del orbital 1 y el piano del anillo aromático. Se provee evidencia experimental para predicir la dependencia angular usando una serie de anilinas restringidas estericamente con distintos ángulos de torsion. El recíproco de la vida media de la fosforecencia de estas anilinas tiene una correlación muy satisfactoria con la función teórica, lo cual apoya el uso del elemento matricial spin‐órbita.
AN ULTRAVIOLET PULSE GENERATOR IN THE SUBMICROSECOND RANGE FOR FLASH PHOTOLYSIS STUDIES
Authors: DALESSIO J. T. , PANTALEONE A. , ZAMPACH J. 
Published: January 2008

ResumenLos métodos experimentales que se emplean en la actualidad par identificar el electrón hidratado y otras especies transientes no pueden extenderse a escala de tiempos más cortos (10‐7–10‐8 seg), que se requiere para la observación de moléculas excitadas de corta vida, que son precursoras de estas especies transientes, sin sustancial desarrollo. Para alcanzar estos tiempos, los pulsos de excitation sean de electrones, rayos X o luz, así como la luz pulsada para el análisis espectro‐fotométrico debe acortarse en varios órdenes de magnitud. Hemos diseñado un generador de luz ultravioleta y visible que emite pulsos menores que 10‐7 seg y potencia de miles de megavatios. El principio básico consiste en aumentar la tensión de chispa hasta próximo a 100 kV y decrecer la capacidad del circuito de descarga como √V, para mantener la energía de la descarga. Suponemos que estos no son los límites finales de intensidad y tiempo. Para obtener pulsos de luz netos, con tiempo de decrecimiento corto y sin cola se han mejorado considerablemente el circuito elétrico y el montaje del generador. Los primeros resultados en el estudio de transientes de corta vida muestran que esta fuente de luz mejorada permite extender el estudio de transientes en la región de 10‐7 seg.
CORRELATION BETWEEN PHOTOCHEMISTRY AND HIGH‐ENERGY RADIATION CHEMISTRY
Authors: HAMMOND GEORGE S. , CALDWELL RICHARD A. , KING JOHN M. , KRISTINSSON HAUKUR , WHITTEN DAVID G. 
Published: January 2008

Abstract— The initial interactions between high‐energy radiation and a sample of condensed matter are complex. However, soon after the initial phases the excitation energy appears in well‐known forms: ions, free radicals, and molecular excited states. These excited species are the immediate precursors of the stable chemical products. The nature of the chemically significant excited species can be inferred by studying the chemical changes induced in solutes which have been well characterized in photochemical studies.RESUMENLas interacciones iniciales entre radiaciones de alta energía y una muestra de materia condensada son complejas. Sin embargo, Iuego de la faz inicial la energía de excitatión aparace bajo formas bien conocidas: iones, radicates libres y estados moleculares excitados. Estas especies excitadas son las precursoras inmediatas productos dequímicos estables. La naturaleza de las especies excitadas con significado químico puede ser inferida estudiando cambios químicos inducidos en solutos que han sido bien caracterizados en estudios fotoquimicos.
RADIOLYSIS AND PHOTOLYSIS IN THE ADSORBED STATE
Authors: ROJO ENRIQUE A. , MOLINARI MARCELO A. 
Published: January 2008

Abstract— Simultaneous irradiation of gases or liquids adsorbed on high‐surface‐area solids of insulator or semiconductor properties frequently produces a considerable increase in radiolysis yields and selective effects in the distribution of products in comparison with those obtained by irradiation of pure substances. This kind of reaction is also sometimes observed when the solid is irradiated before adding the reactant. The results show that part of the energy absorbed by the solid is transferred by some mechanism to the adsorbate and is able to cause its decomposition. In the present paper some of the most representative experiments in the field are analyzed, with special attention on the interpretation of results and proposed reaction mechanisms.RESUMENLa irradiatión simultanea de gases o líquidos adsorbidos en sólidos de propiedades aisladoras o semi‐conductoras produce en la mayoría de los casos un considerable aumento de productos de radiólisis respecto a los producidos irradiando las substantias puras. Este tipo de reacciones también se produce a veces irradiando el sólido primero y agregando el reactante posteriormente.Estos resultados muestran que parte de la energía recibida por el sólido es trasmitida por algúsn mecanismo a la fase absorbida y empleada en la desd compositión del adsorbato.En el presente trabajo se analizan algunas de las experiencias realizadas y se discuten los resultados e interpretaciones. Se discuten asi mismo las posibilidades futuras en este campo.
PHOTOCHEMICAL REACTIONS OF CARBONYL COMPOUNDS IN SOLUTION‐II. PATERNO‐BÜCHI REACTION AND ENERGY TRANSFER
Authors: YANG N. C. 
Published: January 2008

Abstract— Photosensitization with sensitizers of various triplet energy levels was applied to the addition of 9‐anthraldehyde to 2,3‐dimethyl‐2‐butene in order to determine the nature of two reactive excited states of 9‐anthraldehyde. The results indicate that they are most likely an upper triplet state (T2) and a singlet excited state of 9‐anthraldenyde. In a separate series of experiments, it was demonstrated that Paterno‐Büchi reactions occur concurrently with energy transfers from the triplet state of carbonyl compounds to simple olefins in high efficiency. The triplet state of simple olefins is likely to have a nonplanar configuration after the energy transfer. The possible mechanisms of such transfers are discussed.RESUMENLa fotosensitivación con sentivizadores con varios niveles de energia en el estado triplete fué aplicado a la adición de 9‐antraldehido a 2,3 dimetil‐2‐buteno, con el objeto de deteminar la naturaleza de los estados excitados reactivos del 9‐antraldehido. Los resultados indican que son un estado triplete superior (T2) y un estado singulete del 9‐antraldehido. En una serie separada de experimentos se ha demonstrado que las reacciones de Paterno‐Büchi ocurren con transferencias de energía del estado triplete de compuestos carbonílicos a olefinas simples con eflciencia alta. El estado triplete de olefinas simples parece tener una configuración no planar después de la transferencia de energía. Se discuten los mecanismos posibles de esas transferencias.
SOME PHOTOCHEMICAL REACTIONS OF CONJUGATED ACYCLIC OLEFINS
Authors: CROWLEY KEVIN J. 
Published: January 2008

Abstract— The photochemical isomerizations of acyclic conjugated olefins are reviewed. Emphasis is given to photoisomerizations of conjugated dienes and trienes, while reference is made to allene formation from, and other isomerizations of, olefins conjugated with other unsaturated groups. The wide variety of products which is obtained on irradiation of differently substituted trienes is outlined. The stereochemical course of some of these reactions is discussed in orbital symmetry terms, and the uitlity of such considerations is considered in the context of the stereochemistry of the four isomers of alloocimene.RESUMENEn este trabajo se ha efectuado una revisión de los procesos de isomerizaciones fotoquímicas de olefinas conjugadas acíclicas. Se ha dado especial énfasis a las fotodimerizaciones de dienos y trienos conjugados, al mismo tiempo que se hacen referencias a la formación de alenos y a otras isomerizaciones de olefinas conjugadas con otros grupos no saturados. Se describe lagran variedad de productos obtenidos por irradiación de trienos con distintas sustituciones. Se discute además el curso estereoquímico de esta reacción en términos de simetría orbital y la utilidad de tales consideraciones en relación a la estereoquimica de los cuatro isómeros del aloocimeno.
MECHANISMS OF PHOTOREDUCTIONS AND HYDROGENOLYSIS OF PYRIMIDINE NUCLEOSIDES AND THEIR PHOTODIMERS
Authors: WITKOP BERNHARD 
Published: January 2008

Abstract— Photoreduction of uridine to dihydrouridine in the presence of sodium borohydride is shown to be specific for uridine in nucleic acids. This selective reaction provides a method for the production of dihydrouridine in tRNA and messenger RNA in order to investigate its physiological role. Though the photoreduction stops at the dihydrouridine stage, dihydrouridine undergoes selective hydrogenolysis (dark reaction) to ‐γ‐hydroxypropylurea; this reaction is used analytically to detect dihydrouridine in tRNA, and in sequence studies. Thymidine differs from uridine, as the photoreduction does not stop at the dihydrothymidine level, but there is a rapid hydrogenolysis and ring opening. The mechanism and stereochemistry of the hydrogenolysis of dihydrothymidine, photohydrate of thymidine, and photodimers of thymidine are described. The reaction seems capable of being developed into an analytical procedure to determine the photoproducts formed on u. v. irradiation of DN A.RESUMENSe ha demostrado que la fotorreducción de la uridina a dihidrouridina en presencia de borohidruro de sodioes especifica para uridina en ácidos nucleicos. Esta reacción selectiva provee un mecanismo para la incorporación de dihidrouridina en t‐RNA y “messenger RNA. La fotorreducción se detiene a nivel de la dihidrouridina, que luego mediante una hidrogenólisis forma γ‐hidroxipropil urea, esta reacción se usa para detectar dihidrouridina en t‐RNA. La timidina difiere de la uridina en que la fotorreducción no se detiene a nivel de la dihidrotimidina, sino que sufre una rápida hidrogenólisis con apertura del anillo. Se describen los mecanismos y la estereoquímica de la hidrogenólisis de la dihidrotimidina, fotohidrato de timidina y fotodimero de timidina. La reacción es desarrollada en un procedimiento analítico para determinar los fotoproductos formados en DNA irradiado con luz u.v.
Comparison of the Premier Toxin A and B Assay and the TOX A/B II Assay for Diagnosis of
Clostridium difficile
Infection
Authors: Novak-Weekley Susan M. , Hollingsworth Michele H. 
Published: January 2008

ABSTRACT

Clostridium difficile
causes nosocomial diarrhea and is responsible for complications such as pseudomembranous colitis, megacolon, and perforation. Using 442 stool specimens, we compared the sensitivities and specificities of the Premier toxin A and B (Meridian Bioscience, Inc.) and
C. difficile
TOX A/B II (TechLab, Inc., Blacksburg, VA) immunoassays in the Virology Department of the Kaiser Permanente Regional Reference Laboratories. The Premier toxin A and B assay demonstrated a higher sensitivity (97.44%) and a higher positive predictive value (79.17%) than the
C. difficile
TOX A/B II assay (87.18% and 75.56%, respectively), while assay specificities and negative predictive values were similar. We also performed experiments using serially diluted, purified toxin A and B antigens to understand the basis for assay differences. The two assays’ toxin A antibodies detected toxin A at comparable levels. Preliminary results indicated that the toxin B antibody in the Premier toxin A and B assay could detect toxin B at a concentration of 125 pg/100 μl, while the toxin B antibody in the
C. difficile
TOX A/B II assay could not detect toxin B below a concentration of 250 pg/100 μl. Therefore, the Premier toxin A and B assay provides greater sensitivity than the
C. difficile
TOX A/B II assay, perhaps due to a superior detection ability of its toxin B antibody.
Estrogen Induces Repression of the Breast Cancer and Salivary Gland Expression Gene in an Estrogen Receptor α–Dependent Manner
Authors: Bretschneider Nancy , Brand Heike , Miller Nicola , Lowery Aoife J. , Kerin Michael J. , Gannon Frank , Denger Stefanie 
Published: January 2008

Abstract
The focus of this study is on the expression and regulation of the estrogen-regulated breast cancer and salivary gland expression (BASE) gene that may function as a breast cancer marker. In MCF7 cells, BASE is repressed by estrogen in an estrogen receptor α (ERα)-dependent manner. Promoter analysis of the BASE gene led to the identification of a 2-kb upstream enhancer that harbors binding sites for ERα and FoxA1. The recruitment of both ERα and FoxA1 to this region was shown by chromatin immunoprecipitation analysis. Furthermore, mutation studies and knockdown experiments show a clear separation between gene expression mediated by FoxA1 and ERα-dependent gene regulation. Additionally, we provide information on BASE expression in human breast tumor samples. [Cancer Res 2008;68(1):106–14]
Impact of E2F-1 Expression on Clinical Outcome of Gastric Adenocarcinoma Patients with Adjuvant Chemoradiation Therapy
Authors: Lee Jeeyun , Park Cheol Keun , Park Joon Oh , Lim Taekyu , Park Young Suk , Lim Ho Yeong , Lee Inkyoung , Sohn Tae Sung , Noh Jae Hyung , Heo Jin Seok , Kim Sung , Lim Do Hoon , Kim Kyoung-Mee , Kang Won Ki 
Published: January 2008

Abstract
Purpose: There are no reliable prognostic markers that identify gastric cancer patients who may benefit from adjuvant chemoradiation therapy. E2F-1 was shown to be associated with radiosensitivity and chemosensitivity in certain tumor types. Therefore, we analyzed expression and prognostic significance of E2F-1 along with thymidylate synthase (TS) in R0-resected gastric adenocarcinoma patients, who underwent adjuvant chemoradiation therapy with 5-fluorouracil (5-FU) and leucovorin.
Experimental Design: The chemosensitivity to 5-FU and radiosensitivity were tested in three E2F-1–overexpressed gastric cancer cell lines in vitro. The expressions of TS and E2F-1 were analyzed in 467 R0-resected primary gastric cancer patients, who received adjuvant chemoradiation therapy with 5-FU and leucovorin using tissue microarray.
Results: The E2F-1 immunopositivity rate was 22.2% (103 of 465 samples) with a cutoff value of 5% immunoreactivity, whereas the TS-positive expression occurred in 19.0% of the 463 tumors tested. Using stepwise Cox proportional hazards regression modeling, multivariate analyses showed that the E2F-1 immunopositivity predicted more favorable survival as compared with the E2F-1 immunonegativity with borderline statistical significance [P = 0.050, hazard ratio (HR) = 0.702, 95% confidence interval, 0.487, 1.013]. However, the E2F-1 immunopositivity did not retain its statistical significance at multivariate analysis for predicting disease-free survival (data not shown, P = 0.270), but stage was the only influential factor for disease-free survival in stages IB to IV (M0) patients (P &lt; 0.001). TS immunopositivity did not influence survival (P = 0.459) or disease-free survival (P = 0.447).
Conclusion: E2F-1 is a potentially novel independent prognostic factor that may identify gastric cancer patients who will likely benefit from adjuvant chemoradiation therapy following curative resection.
Oral Silibinin Inhibits In vivo Human Bladder Tumor Xenograft Growth Involving Down-Regulation of Survivin
Authors: Singh Rana P. , Tyagi Alpna , Sharma Girish , Mohan Sarumathi , Agarwal Rajesh 
Published: January 2008

Abstract
Purpose: Chemoprevention is an upcoming approach to control bladder cancer, which is one of the commonly diagnosed malignancies showing recurrence rate of 70% or even higher. Recently, we observed the in vitro efficacy of silibinin, a flavanolignan, in human bladder transitional cell papilloma RT4 cells. Here, we investigated the antitumor efficacy and associated mechanisms of silibinin in RT4 tumor xenograft.
Experimental Design: RT4 tumor xenograft was implanted s.c. in athymic nude mice, and then animals were oral gavaged with silibinin at 100 and 200 mg/kg doses, 5 days/week for 12 weeks. Tumor growth, body weight, and diet consumption were recorded, and tumors were analyzed for proliferation, apoptosis, and angiogenesis biomarkers and molecular alterations by immunohistochemistry, immunoblot analysis, and ELISA. p53 small interfering RNA was used in cell culture to examine the role of p53 in survivin expression.
Results: Silibinin feeding inhibited tumor xenograft growth without any gross signs of toxicity. Silibinin decreased tumor volume by 51% to 58% (P ≤ 0.01) and tumor weight by 44% to 49% (P &lt; 0.05). Silibinin moderately (P &lt; 0.001) decreased cell proliferation and microvessel density and strongly (P &lt; 0.001) increased apoptosis in tumors. Silibinin robustly decreased survivin protein expression and its nuclear localization, as well as tumor-secreted level in mouse plasma, but increased p53 and cleaved caspase-3 levels in tumors. Silibinin-caused decrease in survivin was independent of p53.
Conclusion: These findings identified in vivo antitumor efficacy of silibinin against human bladder tumor cells involving down-regulation of survivin and an increase in p53 expression together with enhanced apoptosis.
War, Peace, and American Politics
Authors: Power Jonathan 
Published: January 2008

Zbigniew Brzezinski remains at 79 the same feisty, acerbic intellectual he has always been, giving little quarter to his opponents. Admired rather than loved, he was, as President Jimmy Carter's national security advisor, the antithesis of the careful, more rounded, secretary of state, Cyrus Vance. Indeed, during that period, he was seen as the voice that gradually dissuaded Carter of his own more pacific inner convictions. He was responsible for the confrontational tone of accusations against the Soviet Union's failings on the human rights front, while at the same time playing down the human rights abuses in friendly countries such as Iran and Pakistan. He was the prime White House voice for secretly arming the mujahidin to fight the Soviets in Afghanistan, even before the Red Army invaded. It was he who persuaded Carter to block Vance's instinct to complete what the Soviets wanted—a further freeze on nuclear arms and instead go for the more demanding course of arms reductions, which badly upset Moscow.
At the same time he was the only one in the foreign policy apparatus with a vision of where America should lead the world. He was the philosopher king of the White House. Thus, it was he who persuaded Carter that it was possible to bring peace to the Middle East and to expend an immense amount of energy in successfully reconciling Israel and Egypt. He saw more clearly than most the importance of the United Nations and encouraged Andrew Young in his remarkably creative and highly unusual ambassadorship to that body.
Today, he has a powerful advisory role in Barack Obama's presidential bid and has emerged as President George W Bush's most searing foreign policy critic.