bluuebunny/crossref_metadata_2025_split huggingface dataset:
P2X7 receptor‐induced death of motor neurons by a peroxynitrite/FAS‐dependent pathway
Authors: Gandelman Mandi , Levy Mark , Cassina Patricia , Barbeito Luis , Beckman Joseph S. 
Published: May 2013

AbstractThe P2X7 receptor/channel responds to extracellular ATP and is associated with neuronal death and neuroinflammation in spinal cord injury and amyotrophic lateral sclerosis. Whether activation of P2X7 directly causes motor neuron death is unknown. We found that cultured motor neurons isolated from embryonic rat spinal cord express P2X7 and underwent caspase‐dependent apoptosis when exposed to exceptionally low concentrations of the P2X7 agonist 2′(3′)‐O‐(4‐Benzoylbenzoyl)‐ATP. The P2X7 inhibitors BBG, oATP, and KN‐62 prevented 2′(3′)‐O‐(4‐Benzoylbenzoyl)‐ATP‐induced motor neuron death. The endogenous P2X7 agonist ATP induced motor neuron death at low concentrations (1‐100 μM). High concentrations of ATP (1 mM) paradoxically became protective due to degradation in the culture media to produce adenosine and activate adenosine receptors. P2X7‐induced motor neuron death was dependent on neuronal nitric oxide synthase‐mediated production of peroxynitrite, p38 activation, and autocrine FAS signaling. Taken together, our results indicate that motor neurons are highly sensitive to P2X7 activation, which triggers apoptosis by activation of the well‐established peroxynitrite/FAS death pathway in motor neurons.
The role of tetrahydrobiopterin and catecholamines in the developmental regulation of tyrosine hydroxylase level in the brain
Authors: Homma Daigo , Katoh Setsuko , Tokuoka Hirofumi , Ichinose Hiroshi 
Published: May 2013

AbstractTyrosine hydroxylase (TH) is a rate‐limiting enzyme for dopamine synthesis and requires tetrahydrobiopterin (BH4) as an essential cofactor. BH4 deficiency leads to the loss of TH protein in the brain, although the underlying mechanism is poorly understood. To give insight into the role of BH4 in the developmental regulation of TH protein level, in this study, we investigated the effects of acute and subchronic administrations of BH4 or dopa on the TH protein content in BH4‐deficient mice lacking sepiapterin reductase. We found that BH4 administration persistently elevated the BH4 and dopamine levels in the brain and fully restored the loss of TH protein caused by the BH4 deficiency in infants. On the other hand, dopa administration less persistently increased the dopamine content and only partially but significantly restored the TH protein level in infant BH4‐deficient mice. We also found that the effects of BH4 or dopa administration on the TH protein content were attenuated in young adulthood. Our data demonstrate that BH4 and catecholamines are required for the post‐natal augmentation of TH protein in the brain, and suggest that BH4 availability in early post‐natal period is critical for the developmental regulation of TH protein level.
Frequency of hyperbolic and interstellar meteoroids
Authors: Hajduková Maria , Kornoš Leonard , Tóth Juraj 
Published: May 2013

AbstractHyperbolic meteor orbits from the catalog of 64,650 meteors observed by the multistation video meteor network located in Japan (SonotaCo 2009) have been investigated with the aim of determining the relation between the frequency of hyperbolic and interstellar meteors. The proportion of hyperbolic meteors in the data decreased significantly (from 11.58% to 3.28%) after a selection of quality orbits, which shows its dependence on the quality of observations. Initially, the hyperbolic orbits were searched for meteors unbound due to planetary perturbation. It was determined that 22 meteors from the 7489 hyperbolic orbits in the catalog (and 2 from the selection of the orbits with the highest quality) had had a close encounter with a planet, none of which, however, produced essential changes in their orbits. Similarly, the fraction of hyperbolic orbits in the data, which could be hyperbolic by reason of a meteor's interstellar origin, was determined to be at most 3.9 × 10−2. From the statistical point of view, the vast majority of hyperbolic meteors in the database have definitely been caused by inaccuracy in the velocity determination. This fact does not necessarily assume great measurement errors, since, especially near the parabolic limit, a small error in the value of the heliocentric velocity of a meteor can create an artificial hyperbolic orbit that does not really exist. The results show that the remaining 96% of meteoroids with apparent hyperbolic orbits belong to the solar system meteoroid population. This is also supported by their high abundance (about 50%) among the meteor showers.
Nanomechanical analysis of pigmented human melanoma cells
Authors: Sarna Michal , Zadlo Andrzej , Pilat Anna , Olchawa Magdalena , Gkogkolou Paraskevi , Burda Kvetoslava , Böhm Markus , Sarna Tadeusz 
Published: May 2013

SummaryBased on hitherto measurements of elasticity of various cells in vitro and ex vivo, cancer cells are generally believed to be much softer than their normal counterparts. In spite of significant research efforts on the elasticity of cancer cells, only few studies were undertaken with melanoma cells. However, there are no reports concerning pigmented melanoma cells. Here, we report for the first time on the elasticity of pigmented human melanoma cells. The obtained data show that melanin significantly increases the stiffness of pigmented melanoma cells and that the effect depends on the amount of melanin inside the cells. The dramatic impact of melanin on the nanomechanical properties of cells puts into question widely accepted paradigm about all cancer cells being softer than their normal counterparts. Our findings reveal significant limitations of the nanodiagnosis approach for melanoma and contribute to better understanding of cell elasticity.
Photoreduction of Azaoxoisoaporphines by Amines: Laser Flash and Steady‐State Photolysis and Pulse Radiolysis Studies
Authors: de la Fuente Julio R. , Aliaga Christian , Cañete Alvaro , Kciuk Gabriel , Szreder Tomasz , Bobrowski Krzysztof 
Published: May 2013

AbstractPhotoreduction of 7H‐benzo[e]perimidin‐7‐one (3‐AOIA, A1) and its 2‐methyl derivative (2‐Me‐3‐AOIA, A2) by non‐H‐donating amines (1,4‐diazabicyclo[2.2.2]octane [DABCO]; 2,2,6,6‐tetramethylpiperidine [TMP]), and a hydrogen‐donating amine (triethylamine [TEA]), has been studied in deaerated neat acetonitrile solutions using laser flash photolysis (LFP) and steady‐state photolysis. The triplet excited states of A1 and A2 were characterized by a strong absorption band with λmax = 440 nm and lifetimes of 20 and 27 μs respectively. In the presence of tertiary amines, both triplet excited states were quenched with rate constants close to the diffusional limit (kq ranged between 109 and 1010 M−1 s−1). The transient absorption spectra observed after quenching with DABCO and TMP were characterized by maxima located at 460 nm and broad shoulders in the range of 500–600 nm. These transient species are attributed to solvent‐separated radical ion pairs and/or to isolated radical anions. In the presence of TEA, these transients undergo proton transfer, leading to the neutral hydrogenated radicals, protonated over the N1‐ and O‐atoms. Transient absorption spectra of these transients were characterized by maxima located at 400 and 520 nm and 430 nm respectively. Additional support for these spectral assignments was provided by pulse radiolysis (PR) experiments in acetonitrile and 2‐propanol solutions.
Study of the Mode and Efficiency of DNA Binding in the Damage Induced by Photoactivated Water Soluble Porphyrins
Authors: Karunakaran Suneesh C. , Ramaiah Danaboyina , Schulz Ina , Epe Bernd 
Published: May 2013

AbstractWe have investigated the DNA binding interactions and in vitro photoactivated DNA damage induced by a neutral water soluble porphyrin derivative 5,10,15,20‐tetrakis(2,4,6‐trihydroxyphenyl)porphyrin (TTHPP) and its zinc derivative 5,10,15,20‐tetrakis(2,4,6‐trihydroxyphenyl)porphyrinato zinc(II) (Zn‐TTHPP) upon visible light irradiation through various spectroscopic techniques and employing repair endonucleases. These porphyrin derivatives exhibited high affinity toward DNA through groove binding interactions as evidenced through the UV–vis absorption, emission, circular dichroism spectral and viscosity changes. Interestingly, the free base porphyrin derivative, TTHPP generated efficient singlet oxygen mediated DNA damage sensitive to formamidopyrimidine‐DNA glycosylase (Fpg protein), when compared with its metal derivative and to the well‐known photosensitizer, hematoporphyrin. These results provide direct evidence for the role of DNA binding mode as well as extent of interactions with DNA in the efficiency of photoactivated DNA damage induced by the neutral porphyrins, which are believed to be the ideal candidates for photodynamic therapeutic applications.
In Situ Synthesis and Characterization of Nano ZnO on Wool: Influence of Nano Photo Reactor on Wool Properties
Authors: Montazer Majid , Amiri Morteza Maali , Mohammad Ali Malek Reza 
Published: May 2013

AbstractThis study has been carried out to synthesize nano ZnO on wool fabric and also to investigate influences of nano photo reactors on wool fabric characteristics. Zinc acetate has been used as a precursor and the synthesis process has been done in water and water/ethanol media. The treated wool fabrics were heated at 80°C for 10 h to dehydrate Zn(OH)2 obtaining ZnO. The fabric samples were then subjected to daylight for 7 days to examine the influence of nano ZnO photo reactor on the fabric properties. SEM images revealed the embedding of ZnO nanoparticles on the fabrics and X‐ray diffraction verified the nanoparticles composition. The Yellowness Index (YI) of the fabrics was measured with Color Eye XTH that has been reduced with increasing pH, Zn(CH3COO)2 concentration, ethanol and heating. The lower water contact angle and time of water absorption confirmed higher hydrophilic properties of the treated fabrics. Interestingly, a higher tensile strength obtained on the wool fabrics proved the interaction of ZnO with protein chains of wool, which was verified through lower alkali solubility of treated fabric with nano ZnO and confirmed more benefits of the in situ synthesis process.
Consecutive transcranial magnetic stimulation twitches reduce flow limitation during sleep in apnoeic patients
Authors: Melo‐Silva César Augusto , Gakwaya Simon , Rousseau Eric , Sériès Frédéric 
Published: May 2013

New Findings
What is the central question of this study?A transcranial magnetic stimulation (TMS)‐induced twitch applied on isolated single breaths over the motor cortex somatotopic representation of the tongue briefly recruits submental muscles and improves airflow dynamics of flow‐limited respiratory cycles without arousing sleep apnoea patients. However, the mechanical impact of the TMS‐induced twitch applied during consecutive breathing cycles on airflow dynamics remains unknown.
What is the main finding and what is its importance?Our results show that application of TMS with the stimulator output set at the sleep submental motor threshold intensity on consecutive respiratory cycles increases inspiratory flow and reduces the turbulent airflow component. These results indicate an improvement of airflow pattern after two single consecutive TMS‐induced twitches without arousing sleep apnoea patients.
Transcranial magnetic stimulation (TMS)‐induced twitches applied on isolated breaths briefly recruit upper airway dilator muscles and improve airflow and inspiratory volume without arousing apnoeic patients from sleep, but the effects of applying such twitches consecutively on airflow dynamics is unknown. The objective of this study was to quantify the effects of five consecutive TMS‐induced twitches applied on sleep‐induced obstructive hypopnoeic breaths in 10 obstructive sleep apnoea patients. Submental muscle motor threshold (SUBMT) and motor‐evoked potential were measured during wakefulness and sleep. The TMS‐induced twitches were applied during stable non‐rapid eye movement (NREM) sleep, at the beginning of inspiration of consecutive flow‐limited respiratory cycles, with the stimulator output set at sleep SUBMT. Maximal inspiratory flow, inspiratory volume, inspiratory time, shifts of electroencephalogram frequency and pulse rate variability were assessed. During sleep, SUBMT increased (wakefulness, 25.3 ± 4.9%; NREM sleep, 27.0 ± 6.2%; P= 0.02). During each series of stimulations there was a rise in maximal inspiratory flow (from 306.7 ± 123.2 to 359.8 ± 154.1 ml s−1; P= 0.0002) and in inspiratory volume (from 346.1 ± 128.1 to 414.9 ± 171.2 ml; P= 0.02) without differences in thoraco‐abdominal efforts and inspiratory time. These responses were observed in the absence of arousals and ceased immediately after TMS interruption. Transcranial magnetic stimulation‐induced cortical and/or autonomic arousal was observed in 30.2% of all series of stimulation. Consecutive twitch TMS of submental muscles may lead to arousals in a minority of patients but can be applied on consecutive respiratory cycles during sleep and can significantly improve maximal inspiratory flow and inspiratory volume of flow‐limited cycles.
New Group in the Leptospirillum Clade: Cultivation-Independent Community Genomics, Proteomics, and Transcriptomics of the New Species “Leptospirillum Group IV UBA BS”
Authors: Goltsman Daniela S. Aliaga , Dasari Mauna , Thomas Brian C. , Shah Manesh B. , VerBerkmoes Nathan C. , Hettich Robert L. , Banfield Jillian F. 
Published: May 2013

ABSTRACT

Leptospirillum
spp. are widespread members of acidophilic microbial communities that catalyze ferrous iron oxidation, thereby increasing sulfide mineral dissolution rates. These bacteria play important roles in environmental acidification and are harnessed for bioleaching-based metal recovery. Known members of the
Leptospirillum
clade of the
Nitrospira
phylum are
Leptospirillum ferrooxidans
(group I),
Leptospirillum ferriphilum
and “
Leptospirillum rubarum
” (group II), and
Leptospirillum ferrodiazotrophum
(group III). In the Richmond Mine acid mine drainage (AMD) system, biofilm formation is initiated by
L. rubarum
;
L. ferrodiazotrophum
appears in later developmental stages. Here we used community metagenomic data from unusual, thick floating biofilms to identify distinguishing metabolic traits in a rare and uncultivated community member, the new species “
Leptospirillum
group IV UBA BS.” These biofilms typically also contain a variety of
Archaea
,
Actinobacteria
, and a few other
Leptospirillum
spp. The
Leptospirillum
group IV UBA BS species shares 98% 16S rRNA sequence identity and 70% average amino acid identity between orthologs with its closest relative,
L. ferrodiazotrophum
. The presence of nitrogen fixation and reverse tricarboxylic acid (TCA) cycle proteins suggest an autotrophic metabolism similar to that of
L. ferrodiazotrophum
, while hydrogenase proteins suggest anaerobic metabolism. Community transcriptomic and proteomic analyses demonstrate expression of a multicopper oxidase unique to this species, as well as hydrogenases and core metabolic genes. Results suggest that the
Leptospirillum
group IV UBA BS species might play important roles in carbon fixation, nitrogen fixation, hydrogen metabolism, and iron oxidation in some acidic environments.
Enzymatic Synthesis and Characterization of Fructooligosaccharides and Novel Maltosylfructosides by Inulosucrase from Lactobacillus gasseri DSM 20604
Authors: Díez-Municio Marina , de las Rivas Blanca , Jimeno Maria Luisa , Muñoz Rosario , Moreno F. Javier , Herrero Miguel 
Published: May 2013

ABSTRACT

The ability of an inulosucrase (IS) from
Lactobacillus gasseri
DSM 20604 to synthesize fructooligosaccharides (FOS) and maltosylfructosides (MFOS) in the presence of sucrose and sucrose-maltose mixtures was investigated after optimization of synthesis conditions, including enzyme concentration, temperature, pH, and reaction time. The maximum formation of FOS, which consist of β-2,1-linked fructose to sucrose, was 45% (in weight with respect to the initial amount of sucrose) and was obtained after 24 h of reaction at 55°C in the presence of sucrose (300 g liter
−1
) and 1.6 U ml
−1
of IS–25 mM sodium acetate buffer–1 mM CaCl
2
(pH 5.2). The production of MFOS was also studied as a function of the initial ratios of sucrose to maltose (10:50, 20:40, 30:30, and 40:20, expressed in g 100 ml
−1
). The highest yield in total MFOS was attained after 24 to 32 h of reaction time and ranged from 13% (10:50 sucrose/maltose) to 52% (30:30 sucrose/maltose) in weight with respect to the initial amount of maltose. Nuclear magnetic resonance (NMR) structural characterization indicated that IS from
L. gasseri
specifically transferred fructose moieties of sucrose to either C-1 of the reducing end or C-6 of the nonreducing end of maltose. Thus, the trisaccharide erlose [α-
d
-glucopyranosyl-(1→4)-α-
d
-glucopyranosyl-(1→2)-β-
d
-fructofuranoside] was the main synthesized MFOS followed by neo-erlose [β-
d
-fructofuranosyl-(2→6)-α-
d
-glucopyranosyl-(1→4)-α-
d
-glucopyranose]. The formation of MFOS with a higher degree of polymerization was also demonstrated by the transfer of additional fructose residues to C-1 of either the β-2,1-linked fructose or the β-2,6-linked fructose to maltose, revealing the capacity of MFOS to serve as acceptors.
Low-pH Rescue of Acid-Sensitive Salmonella enterica Serovar Typhi Strains by a Rhamnose-Regulated Arginine Decarboxylase System
Authors: Brenneman Karen E. , Willingham Crystal , Kong Wei , Curtiss Roy , Roland Kenneth L. 
Published: May 2013

ABSTRACT

For
Salmonella
, transient exposure to gastric pH prepares invading bacteria for the stresses of host-cell interactions. To resist the effects of low pH, wild-type
Salmonella enterica
uses the acid tolerance response and the arginine decarboxylase acid resistance system. However, arginine decarboxylase is typically repressed under routine culture conditions, and for many live attenuated
Salmonella
vaccine strains, the acid tolerance response is unable to provide the necessary protection. The objective of this study was to enhance survival of
Salmonella enterica
serovar Typhi vaccine strains at pHs 3.0 and 2.5 to compensate for the defects in the acid tolerance response imposed by mutations in
rpoS
,
phoPQ
, and
fur
. We placed the arginine decarboxylase system (
adiA
and
adiC
) under the control of the P

araBAD

or P

rhaBAD

promoter to provide inducible acid resistance when cells are grown under routine culture conditions. The rhamnose-regulated promoter P

rhaBAD

was less sensitive to the presence of its cognate sugar than the arabinose-regulated promoter P

araBAD

and provided tighter control over
adiA
expression. Increased survival at low pH was only observed when
adiA
and
adiC
were coregulated by rhamnose and depended on the presence of rhamnose in the culture medium and arginine in the challenge medium. Rhamnose-regulated acid resistance significantly improved the survival of Δ
aroD
and Δ
phoPQ
mutants at pHs 3 and 2.5 but only modestly improved the survival of a
fur
mutant. The construction of the rhamnose-regulated arginine decarboxylase system allowed us to render
S
. Typhi acid resistant (to pH 2.5) on demand, with survival levels approximately equivalent to that of the native arginine decarboxylase system.
Enterococcal Rgg-Like Regulator ElrR Activates Expression of the
elrA
Operon
Authors: Dumoulin Romain , Cortes-Perez Naima , Gaubert Stephane , Duhutrel Philippe , Brinster Sophie , Torelli Riccardo , Sanguinetti Maurizio , Posteraro Brunella , Repoila Francis , Serror Pascale 
Published: May 2013

ABSTRACT

The
Enterococcus faecalis
leucine-rich protein ElrA promotes virulence by stimulating bacterial persistence in macrophages and production of the interleukin-6 (IL-6) cytokine. The ElrA protein is encoded within an operon that is poorly expressed under laboratory conditions but induced
in vivo
. In this study, we identify
ef2687
(renamed
elrR
), which encodes a member of the Rgg (
r
egulator
g
ene for
g
lucosyltransferase) family of putative regulatory proteins. Using quantitative reverse transcription-PCR, translational
lacZ
fusions, and electrophoretic mobility shift assays, we demonstrate that ElrR positively regulates expression of
elrA
. These results correlate with the attenuated virulence of the Δ
elrR
strain in a mouse peritonitis model. Virulence of simple and double
elrR
and
elrA
deletion mutants also suggests a remaining ElrR-independent expression of
elrA in vivo
and additional virulence-related genes controlled by ElrR.
Dissecting the Metal Selectivity of MerR Monovalent Metal Ion Sensors in Salmonella
Authors: Ibáñez María M. , Cerminati Sebastián , Checa Susana K. , Soncini Fernando C. 
Published: May 2013

ABSTRACT

Two homologous transcription factors, CueR and GolS, that belong to the MerR metalloregulatory family are responsible for
Salmonella
Cu and Au sensing and resistance, respectively. They share similarities not only in their sequences, but also in their target transcription binding sites. While CueR responds similarly to Au, Ag, or Cu to induce the expression of its target genes, GolS shows higher activation by Au than by Ag or Cu. We showed that the ability of GolS to distinguish Au from Cu resides in the metal-binding loop motif. Here, we identify the amino acids within the motif that determine
in vivo
metal selectivity. We show that residues at positions 113 and 118 within the metal-binding loop are the main contributors to metal selectivity. The presence of a Pro residue at position 113 favors the detection of Cu, while the presence of Pro at position 118 disfavors it. Our results highlight the molecular bases that allow these regulators to coordinate the correct metal ion directing the response to a particular metal injury.
Ubiquinone and Menaquinone Electron Carriers Represent the Yin and Yang in the Redox Regulation of the ArcB Sensor Kinase
Authors: Alvarez Adrián F. , Rodriguez Claudia , Georgellis Dimitris 
Published: May 2013

ABSTRACT

The Arc two-component system, comprising the ArcB sensor kinase and the ArcA response regulator, modulates the expression of numerous genes in response to respiratory growth conditions. Under aerobic growth conditions, the ubiquinone electron carriers were proposed to silence the kinase activity of ArcB by oxidizing two cytosol-located redox-active cysteine residues that participate in intermolecular disulfide bond formation. Here, we confirm the role of the ubiquinone electron carriers as the silencing signal of ArcB
in vivo
, we show that the redox potential of ArcB is about −41 mV, and we demonstrate that the menaquinols are required for proper ArcB activation upon a shift from aerobic to anaerobic growth conditions. Thus, an essential link in the Arc signal transduction pathway connecting the redox state of the quinone pool to the transcriptional apparatus is elucidated.