bluuebunny/crossref_metadata_2025_split huggingface dataset:
CHEMIEXCITATION IN THE PEROXIDATIVE METABOLISM OF N‐METHYLCARBAZOLE: MECHANISTIC IMPLICATIONS
Authors: de Melo Mariza Pires , Cilento Giuseppe 
Published: January 2008

Abstract: The peroxidative metabolism of N‐methylcarbazole emits light independently of the presence of oxygen. It is likely that two chemiexcited transients are formed by electron transfer to the activated peroxidase, the cation radical by one electron transfer and a cation biradical by two electron transfer consistent with the failure to observe horseradish peroxidase‐II in the steady state of the reaction. In the spectral range investigated (390–700 nm) the observed emission (570–700 nm) is ascribed to the biradical, as the latter is equivalent to an excited state of the postulated iminium cation.While lipoxygenase has no effect upon N‐methylcarbazole, it markedly enhances the emission if peroxidase is present. This effect requires oxygen and is ascribed to an excited product formed by lipoxygenase acting upon an intermediate hydroperoxide of the aerobic process promoted by peroxidase.Our results are of importance on two counts. First they extend to N‐rnethylcarbazole the formation of excited species in the peroxidative metabolism of important xenobiotics. Second, the mechanistic information they provide supports the scheme of metabolism postulated by Kedderis et al. (1986, J. Biol. Chem. 261, 15910–15914).
Exclusive Free Radical Mechanisms of Cellular Photosensitization
Authors: Aveline Beatrice M. , Redmond Robert W. 
Published: January 2008

ABSTRACTIn order to determine the specific effects of radical‐induced reactions in the absence of complicating excited‐state pathways, four different thiohydroxamic esters and their parent molecule,N‐hydroxypyridine‐2(1H)‐thione, have been studied in murine L1210 leukemia cells for their ability to produce photobiological damage. Irradiation (Xexc= 355 nm) of cells in the presence of thiopyridone esters, specific photolytic precursors of sulfur‐, carbon‐ and oxygen‐centered radicals, caused toxicity that was unambiguously demonstrated to result from radical photosensitization mechanisms. Cellular morphological changes were observed following irradiation but apoptosis was not found to take place. A good correlation was evident between lipid peroxidation, measured by the thiobarbituric acid method, and phototoxicity, assessed by the trypan blue exclusion assay, indicating that the ester derivatives exert their effects mainly in plasma and/ or subcellular membranes. Irradiation performed under deaerated conditions also induced significant phototoxicity but the effects of deaeration were dependent on the ester used and are discussed in terms of the nature of the primary radical species generated in each case. Irradiation of L1210 cells in the presence ofN‐hydroxypyridine‐2(1H)‐thione, a nonspecific, photochemical source of hydroxyl radical, was also found to trigger phototoxicity and lipid peroxidation. However in this case, photodamage cannot yet be definitely attributed to a radical or type II mechanism although the apparent oxygen independence of phototoxicity would indicate that type II contribution is not significant.
Light Dosimetry for Intraperitoneal Photodynamic Therapy in a Murine Xenograft Model of Human Epithelial Ovarian Carcinoma
Authors: Lilge Lothar , Molpus Kelly , Hasan Tayyaba , Wilson Brian C. 
Published: January 2008

ABSTRACTFew studies have been published to date measuring spatially resolved fluence rates in complex tissue geometries. Here the light distributions of three different intraperitoneal light delivery geometries in a murine ovarian cancer model were investigated to assess their influence on the tumorcidal efficacy of photodynamic therapy (PDT). In vivo fluence rate measurements in the peritoneal cavities of mice, with the light intensity being mapped in three transverse planes, were performed using fiber‐optic detectors. Three different source fiber designs and placements were tested for their ability to provide uniform irradiation of the peritoneal cavity. The biological response to a PDT protocol comprising three separate treatments administered at 72 h intervals, each consisting of a 0.25 mg kg intraperitoneal injection of benzopor‐phyrin derivative‐mono acid ring A followed 90 min later by delivery of 15 J of 690 nm light, was measured. The tissue response was evaluated by measuring the number of remaining visible lesions and the total residual tumor mass. Fluence rate measurements showed large variations in the fluence rate distribution for similar intended treatments. The most uniform and reproducible illumination was achieved using two 18 mm long cylindrical emitting optical fibers. The biological response was comparable to that produced when a flat‐cleaved end optical fiber is used to illuminate the four quadrants of the abdomen sequentially. While a good reproducibility in tumor induction in this animal model exists, no correlation was found between the fluence rate distribution measured in one group of animals and the biological response in a separate group of similarly treated animals. Due to the large intra‐animal variability in fluence rate distribution, representative fluence rate mapping in complex tissue geometries is of limited value when applied to an individual PDT treatment. Thus, surveillance of the fluence rate during individual treatments will be required for acceptable PDT dosimetry. To improve the versatility of this particular animal model for PDT research, a large number of extended sources are required to increase uniformity of the illumination in order to reduce unwanted cytotoxic side effects resulting from foci of high fluence rates. In this way, subsequent increase of the total energy delivered to the tumor may be possible.
Probing the Binding Region of the Single‐Stranded DNA‐Binding Domain of Rat DNA Polymerase β Using Nanosecond‐Pulse Laser‐Induced Cross‐Linking and Mass Spectrometry
Authors: Connor Dallas A. , Falick Arnold M. , Young Mark C. , Shetlar Martin D. 
Published: January 2008

ABSTRACTIn recent years, there has been a significant number of studies in which UV light has been used as a reagent to induce cross‐links in nucleic acid‐protein complexes. An area of considerable interest among those interested in structural biology is the garnering of information about the sites of cross‐linking within the protein and nucleic acid members of photolinked conjugates, under the assumption that such knowledge should lead to identification of contact regions or sites within the native complexes. In this paper, we present our results from a photocross‐linking study of the complex of the single‐stranded DNA‐binding domain of rat DNA polymerase β (pol β‐ss) with the oligonucleotide d(ATATATA). In this study, we have used single nanosecond laser pulses as the cross‐linking reagent and matrix‐assisted laser desorp‐tion/ionization‐time of flight mass spectrometry as an analytical tool to identify cross‐linked peptides purified from proteolytic digests of the cross‐linked complex. Six cross‐linked peptides have been identified in tryptic digests of the protein‐oligonucleotide conjugates that result from irradiation of the pol β‐ss‐d(ATATATA) complex with a single laser pulse. Comparisons with NMR data in the literature for the same complex show that each of the cross‐linked peptides contains amino acids that are in contact with the nucleic acid component of the complex.
Porphyrins and Related Compounds as Photoactivatable Insecticides. 2. Phototoxic Activity of Meso‐Substituted Porphyrins
Authors: Amor T. Ben , Bortolotto L. , Jori G. 
Published: January 2008

ABSTRACTWe have recently proposed the use of porphyrin sensitizers as photoinsecticidal agents. Our present findings show that the phototoxic efficiency of porphyrins toward the Mediterranean fruit fly Ceratitis capitata is strongly dependent on their chemical structure. Thus, two highly hydrophilic porphyrins, such as a tetraanionic and a te‐tracationic meso‐substituted derivative, show a very low photoactivity even upon prolonged irradiation with full‐spectrum visible light. The phototoxicity increases upon increasing the hydrophobicity of the porphyrin molecule; out of the compounds examined by us, the highest pho‐tocidal activity is exhibited by a dicationic amphophilic porphyrin, namely cis‐(JV‐methyl‐piridyl), c/s‐diphenyl‐porphine, which causes 100% mortality upon 1 h irradiation with a fluence rate of 1220 μ.E s‐lm‐2even at a concentration as low as 0.85 mM. The differences in photoactivity are not related to differences in the photo‐physical and photobiological properties or to differences in the rate of porphyrin uptake and clearance by the flies.
Release of Inflammatory Mediators (PGE2, IL‐6) by Fenofibric Acid‐Photosensitized Human Keratinocytes and Fibroblasts
Authors: Terencio Mari Carmen , Guillen Isabel , Gomez‐Lechon Marfa Jose , Miranda Miguel A. , Castell Jose V. 
Published: January 2008

ABSTRACTUltraviolet‐A radiation has weak effects on the release of inflammatory mediators by skin cells due to the poor overlap between UVA wavelengths and the absorption spectra of the relevant chromophores of key biomole‐cules. However, this situation could be very different in the presence of a photosensitizing drug. To investigate this issue, we have irradiated human skin cells (keratinocytes and fibroblasts) in the presence of fenofibric acid (the active phototoxic metabolite of fenofibrate). The results of this research show a dual effect on the production/release of inflammatory mediators: the synthesis of the proinflammatory cytokine interleukin‐6 becomes strongly inhibited at photosensitizer concentrations that clearly stimulate the production of prostaglandins (PGE2) by skin cells. We have found evidences showing that the de novo synthesis of cytokines is inhibited in photosensitized cells due to the fact that cellular mRNA is degraded. Interestingly, when the medium taken from irradiated cultures is added to nonexposed cells, a significant stimulation of cytokine synthesis is observed that can be inhibited by anti‐PGE2 antibodies. These observations may be relevant in vivo, where prostaglandins released by photosensitized skin cells could stimulate cytokine synthesis by underlying, nonirradiated cells.
Photoelectrochemical Verification of Proton‐Releasing Groups in Bacteriorhodopsin
Authors: Koyama Koichi , Miyasaka Tsutomu , Needleman Richard , Lanyi Janos K. 
Published: January 2008

ABSTRACTLight‐induced transient currents of bacteriorhodopsin (bR) and its mutants (D96N, D85N, E204Q and E194Q) were measured at the interface of an electrode and the aqueous solution in an electrochemical cell. The transient positive (cathodic) and negative (anodic) photocurrents generated upon the onsets of continuous illumination and of turning off light, respectively, were investigated at different electrolyte pH. The wild type exhibits both positive and negative responses, with the sign of the response inverted at pH lt 5. In D85N the response is entirely suppressed, while D96N lacks the negative response. Laser pulse excitation (532 nm) of bR and the mutants showed the response rise time of the positive transient to be uniformly about 100 μs, indicating that the response is linked to the L to M transition in the photocycle. According to these results the positive and negative signals originate from the proton release and uptake reactions, respectively. Photoexcitation of the mutants E204Q and E194Q that lack protonatable residues at position 204 and 194, respectively, produced a negative response at neutral pH, which indicates that in these proteins proton uptake precedes proton release. This result is consistent with our observations made earlier with pH indicator dyes and demonstrates that Glu‐204 and Glu‐194 constitute the terminal proton release complex in the extracellular region of bR.
Light Irradiation of Mouse Spermatozoa: Stimulation of In Vitro Fertilization and Calcium Signals
Authors: Cohen Natalie , Lubart Rachel , Rubinstein Sara , Breitbart Haim 
Published: January 2008

ABSTRACTIrradiation of mouse spermatozoa by 630 nm He‐Ne laser was found to enhance the intracellular calcium levels and fertilizing potential of these cells. The effect of light on calcium transport and on fertilization rate was abrogated in the absence of Ca2+during the irradiation time, indicating that the effect of light is Ca2+dependent. The stimulatory effect of light on Ca2+uptake was abolished in the presence of a voltage‐dependent Ca2+‐channel inhibitor nifedipine, indicating the involvement of a plasma membrane voltage‐dependent Ca2+channel. Furthermore, the stimulatory effect of light was completely inhibited by the mitochondrial uncoupler FCCP, indicating that laser irradiation might affect the mitochondrial Ca2+transport mechanisms. A causal association between laser irradiation, reactive oxygen species (ROS) generation and sperm function was indicated by studies with ROS scavengers, superoxide dismutase (SOD) and catalase, and exogenous hydrogen peroxide. The SOD treatment, which enhanced H2O2 production, resulted in increased Ca2+uptake and enhanced fertilization rate. On the other hand, catalase, which decomposes H2O2, impaired the light‐induced stimulation in Ca2+uptake and the fertilization rate. Taken together, the data suggest that H2O2 might be involved in the irradiation effects, and indeed laser irradiation enhances the production of H2O2, by spermatozoa. These results indicate that the effect of 630 nm He‐Ne laser irradiation is mediated through the generation of H2O2 by the spermatozoa and that this effect plays a significant role in the augmentation of the sperm cells' capability to fertilize metaphase H‐arrested eggs in vitro.
Blue Light Requirement for HC03 Uptake and Its Action Spectrum in Monoraphidium braunii
Authors: Giráldez N. , Aparicio P. J. , Quiñones M. A. 
Published: January 2008

ABSTRACTThe uptake and assimilation of HCO3 by the green unicellular alga Monoraphidium braunii can be monitored by the alkalinization of the external medium or by the O2 evolution associated with the uptake and reduction of this anion. The activation of HCO3 uptake in this microalga required the irradiation of the cell suspensions with low photon fluence rates of short wavelength radiation. Thus, when the cells were irradiated with strong red light in the presence of HCO3, very little alkalinization of the external medium or O2 evolution could be observed. The O2 evolution rates measured under red light could be due to the assimilation of the CO2 derived from the HCO3 present in the medium. The blue light‐dependent O2 evolution rates were not diminished by a periplasmic carbonic anhydrase inhibitor, suggesting that HCO3 ‐dependent O2 evolution was due to the photoactivation of a selective HCO3 uptake system at the plasma membrane. The action spectrum for HCO3‐ uptake in M. braunii was very similar to those reported for NO3‐ and CI‐ suggested that a flavoprotein may be the photoreceptor for this response.
Selection for High-Level Telithromycin Resistance in
Staphylococcus aureus
Yields Mutants Resulting from an
rplB
-to-
rplV
Gene Conversion-Like Event
Authors: Gentry Daniel R. , Holmes David J. 
Published: January 2008

ABSTRACT

While most
Staphylococcus aureus
telithromycin-resistant mutants isolated in this study possessed duplications within
rplV
(encoding ribosomal protein L22), four isolates possessed insertions within
rplV
that were identical to a portion of the gene
rplB
(encoding ribosomal protein L2). This novel type of mutation is the result of an apparent gene conversion-like event.
Reliability of the WIDERYST Susceptibility Testing System for Detection of In Vitro Antifungal Resistance in Yeasts
Authors: Cuenca-Estrella Manuel , Gomez-Lopez Alicia , Gutierrez M. Olga , Buitrago M. Jose , Rodriguez-Tudela Juan L. 
Published: January 2008

ABSTRACT

This study evaluated the WIDERYST system, a commercially available computer-assisted image-processing device for the antifungal susceptibility testing of yeasts. A collection of 90 clinical isolates selected to represent ranges of susceptibilities in vitro as broad as possible was tested. An evaluation compared the results obtained by the new system with those achieved by both the Clinical and Laboratory Standards Institute (CLSI) microdilution reference procedure and the antifungal susceptibility standard of the European Committee for Antimicrobial Susceptibility Testing (EUCAST). Overall, the agreement and the correlation index between results obtained by the EUCAST method and the WIDERYST system were 89% and 0.84 (
P
< 0.01), respectively, and agreement and correlation index between data obtained by the CLSI procedure and the WIDERYST system were 90% and 0.86 (
P
< 0.01), respectively. The system was able to detect amphotericin B-resistant isolates. All
Candida
sp. isolates with resistance in vitro to azole agents were detected as well. The system misclassified some isolates belonging to the slowly growing genera
Dipodascus
and
Pichia
. A total of 2.7% very major errors were detected for fluconazole. The WIDERYST system is an alternative to reference procedures for antifungal susceptibility testing of clinical isolates of yeasts, particularly for
Candida
and
Cryptococcus
species.
Acinetobacter radioresistensas a Silent Source of Carbapenem Resistance forAcinetobacterspp
Authors: Poirel Laurent , Figueiredo Samy , Cattoir Vincent , Carattoli Alessandra , Nordmann Patrice 
Published: January 2008

ABSTRACTCarbapenem resistance results mostly from the expression of acquired carbapenem-hydrolyzing oxacillinases inAcinetobacter baumannii. TheblaOXA-23oxacillinase gene is increasingly reported worldwide and may represent an emerging threat. Our goal was to identify the progenitor of that carbapenemase gene. A collection of 50Acinetobactersp. strains corresponding to severalAcinetobacterspecies was screened forblaOXA-23-like genes by PCR and hybridization techniques. FiveAcinetobacter radioresistensisolates that were susceptible to carbapenems harbored chromosomally encodedblaOXA-23-like genes. A similar plasmid backbone was identified in severalblaOXA-23-positiveA. baumanniiandA. radioresistensisolates, further strengthening the vectors of exchanges for theseblaOXA-23-like genes. Therefore,A. radioresistens, a commensal bacterial species which is identified on the skin of hospitalized and healthy patients (a property shared withA. baumannii), was identified as the source of theblaOXA-23gene.
Bordetella pertussis
Expresses a Functional Type III Secretion System That Subverts Protective Innate and Adaptive Immune Responses
Authors: Fennelly Neil K. , Sisti Federico , Higgins Sarah C. , Ross Pádraig J. , van der Heide Han , Mooi Frits R. , Boyd Aoife , Mills Kingston H. G. 
Published: January 2008

ABSTRACT

Certain bacteria use a type III secretion system (TTSS) to deliver effector proteins that interfere with cell function into host cells. While transcription of genes encoding TTSS components has been demonstrated, studies to date have failed to identify TTSS effector proteins in
Bordetella pertussis
. Here we present the first evidence of a functionally active TTSS in
B. pertussis
. Three known TTSS effectors, Bsp22, BopN, and BopD, were identified as TTSS substrates in
B. pertussis
12743. We found expression of Bsp22 in a significant proportion of clinical isolates but not in common laboratory-adapted strains of
B. pertussis
. We generated a TTSS mutant of
B. pertussis
12743 and showed that it induced significantly lower respiratory tract colonization in mice than the wild-type bacteria. Respiratory infection of mice with the mutant bacteria induced significantly greater innate proinflammatory cytokine production in the lungs soon after challenge, and this correlated with significantly higher antigen-specific interleukin-17, gamma interferon, and immunoglobulin G responses later in infection. Our findings suggest that the TTSS subverts innate and adaptive immune responses during infection of the lungs and may be a functionally important virulence factor for
B. pertussis
infection of humans.
SOME ANALYTIC CALCULATIONS OF THE CHARACTERISTIC EXPONENTS
Authors: VAN DER KLOET P. , NEERHOFF F. L. , WANING N. H. 
Published: January 2008

As is well known, the variational equations of nonlinear dynamic systems are linear time-varying (LTV) by nature. In the modal solutions for these LTV equations, the earlier introduced dynamic eigenvalues play a key role. They are closely related to the Lyapunov- and Floquet-exponents of the corresponding nonlinear systems. In this contribution, we present some simple examples for which analytic solutions exist. It is also demonstrated by example how the classical linear time-invariant (LTI) solutions are related to the equilibrium points of the general LTV solutions.
A single point-mutation within the melanophilin gene causes the lavender plumage colour dilution phenotype in the chicken
Authors: Vaez Mohsen , Follett Sarah A , Bed'hom Bertrand , Gourichon David , Tixier-Boichard Michèle , Burke Terry 
Published: January 2008

Abstract

Background
The lavender phenotype in the chicken causes the dilution of both black (eumelanin) and red/brown (phaeomelanin) pigments. Defects in three genes involved in intracellular melanosomal transport, previously described in mammals, give rise to similar diluted pigmentation phenotypes as those seen in lavender chickens.

Results
We have used a candidate-gene approach based on an expectation of homology with mammals to isolate a gene involved in pigmentation in chicken. Comparative sequence analysis of candidate genes in the chicken identified a strong association between a mutation in the MLPH gene and the diluted pigmentation phenotype. This mutation results in the amino acid change R35W, at a site also associated with similar phenotypes in mice, humans and cats.

Conclusion
This is the first time that an avian species with a mutation in the MLPH gene has been reported.
A pig multi-tissue normalised cDNA library: large-scale sequencing, cluster analysis and 9K micro-array resource generation
Authors: Bonnet Agnès , Iannuccelli Eddie , Hugot Karine , Benne Francis , Bonaldo Maria F , Soares Marcelo B , Hatey François , Tosser-Klopp Gwenola 
Published: January 2008

Abstract

Background
Domestic animal breeding and product quality improvement require the control of reproduction, nutrition, health and welfare in these animals. It is thus necessary to improve our knowledge of the major physiological functions and their interactions. This would be greatly enhanced by the availability of expressed gene sequences in the databases and by cDNA arrays allowing the transcriptome analysis of any function.
The objective within the AGENAE French program was to initiate a high-throughput cDNA sequencing program of a 38-tissue normalised library and generate a diverse microarray for transcriptome analysis in pig species.

Results
We constructed a multi-tissue cDNA library, which was normalised and subtracted to reduce the redundancy of the clones. Expressed Sequence Tags were produced and 24449 high-quality sequences were released in EMBL database. The assembly of all the public ESTs (available through SIGENAE website) resulted in 40786 contigs and 54653 singletons. At least one Agenae sequence is present in 11969 contigs (12.5%) and in 9291 of the deeper-than-one-contigs (22.8%). Sequence analysis showed that both normalisation and subtraction processes were successful and that the initial tissue complexity was maintained in the final libraries. A 9K nylon cDNA microarray was produced and is available through CRB-GADIE. It will allow high sensitivity transcriptome analyses in pigs.

Conclusion
In the present work, a pig multi-tissue cDNA library was constructed and a 9K cDNA microarray designed. It contributes to the Expressed Sequence Tags pig data, and offers a valuable tool for transcriptome analysis.