bluuebunny/crossref_metadata_2025_split huggingface dataset:
Origins of specificity and cross‐talk in metal ion sensing by Bacillus subtilisFur
Authors: Ma Zhen , Faulkner Melinda J. , Helmann John D. 
Published: October 2012

SummaryFur (ferric uptake regulator) is the master regulator of iron homeostasis in many bacteria, but how it responds specifically to Fe(II) in vivo is not clear. Biochemical analyses of Bacillus subtilis Fur (BsFur) reveal that in addition to Fe(II), both Zn(II) and Mn(II) allosterically activate BsFur–DNA binding. Dimeric BsFur co‐purifies with site 1 structural Zn(II) (Fur2Zn2) and can bind four additional Zn(II) or Mn(II) ions per dimer. Metal ion binding at previously described site 3 occurs with highest affinity, but the Fur2Zn2:Me2 form has only a modest increase in DNA binding affinity (approximately sevenfold). Metallation of site 2 (Fur2Zn2:Me4) leads to a ∼ 150‐fold further enhancement in DNA binding affinity. Fe(II) binding studies indicate that BsFur buffers the intracellular Fe(II) concentration at ∼ 1 μM. Both Mn(II) and Zn(II) are normally buffered at levels insufficient for metallation of BsFur site 2, thereby accounting for the lack of cross‐talk observed in vivo. However, in a perR mutant, where the BsFur concentration is elevated, BsFur may now use Mn(II) as a co‐repressor and inappropriately repress iron uptake. Since PerR repression of fur is enhanced by Mn(II), and antagonized by Fe(II), PerR may co‐regulate Fe(II) homeostasis by modulating BsFur levels in response to the Mn(II)/Fe(II) ratio.
High amplitude propagated contractions
Authors: Bharucha A. E. 
Published: October 2012

AbstractWhile most colonic motor activity is segmental and non‐propulsive, colonic high amplitude propagated contractions (HAPC) can transfer colonic contents over long distances and often precede defecation. High amplitude propagated contractions occur spontaneously, in response to pharmacological agents or colonic distention. A subset of patients with slow transit constipation have fewer HAPC. In this issue of Neurogastroenterology and Motility, Rodriguez et al. report that anal relaxation during spontaneous and bisacodyl‐induced HAPC exceeds anal relaxation during rectal distention in constipated children undergoing colonic manometry. Moreover, and consistent with a neural mechanism, anal relaxation often precedes arrival of HAPC in the left colon. High amplitude propagated contractions are also used to evaluate the motor response to a meal and pharmacological stimuli (e.g., bisacodyl, neostigmine) and to identify colonic inertia during colonic motility testing in chronic constipation. This editorial comprehensively reviews the characteristics, physiology and pharmacology of HAPC, their assessment by manometry, and relevance to constipation and diarrhea.
A literature review on flow‐rate variability in neonatal IV therapy
Authors: van der Eijk Anne C. , van Rens Roland M.F.P.T. , Dankelman Jenny , Smit Bert J. 
Published: October 2012

SummaryAimTo provide an overview of factors influencing the flow rate in intravenous (IV) therapy for newborns.MethodsWe conducted a review of the literature from 1980 to 2011 in PubMed and Web of Knowledge. Articles focusing on flow‐rate variability and possible complications due to flow‐rate variability were included.ResultsForty‐one articles were selected for this review. IV therapy in (preterm) neonates is prone to significant start‐up delays and flow‐rate variability. The sudden changes in the volume delivered to (preterm) neonates may have serious consequences. Low preprogrammed flow rates, total compliance, and volume of the IV administration set, the presence or absence of antisiphon valves or inline filters and the vertical displacement of syringe pumps all contribute to flow‐rate variability in IV therapy for neonates.ConclusionsFlow‐rate variability in IV therapy and its clinical relevance are due to the preprogrammed flow rate, the hydrostatic pressure changes, the complete IV administration set compliance and the type of substances supplied to the patient. To improve IV therapy, the internal compliance of the complete IV administration set should be minimized and the highest possible preprogrammed flow rate should be used in combination with small syringes and low‐resistance valves.
Drought stress adaptation: metabolic adjustment and regulation of gene expression
Authors: Bhargava Sujata , Sawant Kshitija 
Published: October 2012

AbstractPlants cope with drought stress by manipulating key physiological processes like photosynthesis, respiration, water relations, antioxidant and hormonal metabolism. There exist multiple and often redundant stress sensors, which transduce the stress signal through secondary signalling molecules to the nucleus, where the expression of stress‐response genes is regulated. Transcription factors play an important role in regulating the expression of the stress‐response genes. Another level of regulation of gene expression is at the epigenetic level and involves modifications either at the chromatin level or at the mRNA level. Crop plants show various adaptive and acclimatization strategies to drought stress, which range from seemingly simple morphological or physiological traits that serve as important stress tolerance markers to major upheavals in gene expression in which a large number of transcription factors are induced. Studies on contrasting crop genotypes or genetic engineering of crops help in differentiating responses to drought from those leading to drought tolerance. Of specific importance to crop plants is not whether they survive stress, but whether they show good yields under stress conditions.
64, XX, SRY‐negative, Testicular DSD Syndrome in a Lusitano Horse
Authors: Torres A , Silva JF , Bernardes N , Sales Luís J , Lopes da Costa L 
Published: October 2012

ContentsHere is reported a disorder of sex development found in the Portuguese Lusitano horse breed. The complex genital phenotype included mammary glands, abdominal testes without epididymis, connected through oviducts to pelvic hypoplastic uterine horns and fused vulvar labia majora from which protruded ventrally a penis‐like structure. This structure was presented in a reversed position, the urethral opening placed dorsally in the glans. However, it was functional both for micturition and erection. The horse exhibited female micturition posture and aggressive male‐like behaviour, including flehmen, mounting, thrusting and flagging of the tail. Plasma testosterone concentrations were below detection limits and the genetic evaluation revealed a 64, XX, SRY‐negative karyotype. Surgery consisted in the removal of abdominal gonads followed by amputation of the penis and repositioning of the urethra. This case of reversion between the chromosomal and gonadal sex, associated with mixed anatomical and behavioural phenotype, illustrates that development of the testes may occur in the absence of the SRY gene and that other genetic and cellular pathways leading to gonad differentiation should be investigated.
Comparative analysis of genome composition in Triticeae reveals strong variation in transposable element dynamics and nucleotide diversity
Authors: Middleton Christopher P. , Stein Nils , Keller Beat , Kilian Benjamin , Wicker Thomas 
Published: October 2012

SummaryA 454 sequencing snapshot was utilised to investigate the genome composition and nucleotide diversity of transposable elements (TEs) for several Triticeae taxa, including Triticum aestivum, Hordeum vulgare, Hordeum spontaneum and Secale cereale together with relatives of the A, B and D genome donors of wheat, Triticum urartu (A), Aegilops speltoides (S) and Aegilops tauschii (D). Additional taxa containing the A genome, Triticum monococcum and its wild relative Triticum boeoticum, were also included. The main focus of the analysis was on the genomic composition of TEs as these make up at least 80% of the overall genome content. Although more than 200 TE families were identified in each species, approximately 50% of the overall genome comprised 12–15 TE families. The BARE1 element was the largest contributor to all genomes, contributing more than 10% to the overall genome. We also found that several TE families differ strongly in their abundance between species, indicating that TE families can thrive extremely successfully in one species while going virtually extinct in another. Additionally, the nucleotide diversity of BARE1 populations within individual genomes was measured. Interestingly, the nucleotide diversity in the domesticated barley H. vulgare cv. Barke was found to be twice as high as in its wild progenitor H. spontaneum, suggesting that the domesticated barley gained nucleotide diversity from the addition of different genotypes during the domestication and breeding process. In the rye/wheat lineage, sequence diversity of BARE1 elements was generally higher, suggesting that factors such as geographical distribution and mating systems might play a role in intragenomic TE diversity.
On the limit behavior of metrics in the continuity method for the Kähler–Einstein problem on a toric Fano manifold
Authors: Li Chi 
Published: October 2012

AbstractThis work is a continuation of the author’s previous paper [Greatest lower bounds on the Ricci curvature of toric Fano manifolds, Adv. Math. 226(2011), 4921–4932]. On any toric Fano manifold, we discuss the behavior of the limit metric of a sequence of metrics which are solutions to a continuity family of complex Monge–Ampère equations in the Kähler–Einstein problem. We show that the limit metric satisfies a singular complex Monge–Ampère equation. This gives a conic-type singularity for the limit metric. Information on conic-type singularities can be read off from the geometry of the moment polytope.
In vitro evaluation of the imaging accuracy of C‐arm conebeam CT in cerebral perfusion imaging
Authors: Ganguly A. , Fieselmann A. , Boese J. , Rohkohl C. , Hornegger J. , Fahrig R. 
Published: October 2012

Purpose:The authors have developed a method to enable cerebral perfusion CT imaging using C‐arm based conebeam CT (CBCT). This allows intraprocedural monitoring of brain perfusion during treatment of stroke. Briefly, the technique consists of acquiring multiple scans (each scan comprised of six sweeps) acquired at different time delays with respect to the start of the x‐ray contrast agent injection. The projections are then reconstructed into angular blocks and interpolated at desired time points. The authors have previously demonstrated its feasibilityin vivo using an animal model. In this paper, the authors describe an in vitro technique to evaluate the accuracy of their method for measuring the relevant temporal signals.Methods:The authors’ evaluation method is based on the concept that any temporal signal can be represented by a Fourier series of weighted sinusoids. A sinusoidal phantom was developed by varying the concentration of iodine as successive steps of a sine wave. Each step corresponding to a different dilution of iodine contrast solution contained in partitions along a cylinder. By translating the phantom along the axis at different velocities, sinusoidal signals at different frequencies were generated. Using their image acquisition and reconstruction algorithm, these sinusoidal signals were imaged with a C‐arm system and the 3D volumes were reconstructed. The average value in a slice was plotted as a function of time. The phantom was also imaged using a clinical CT system with 0.5 s rotation. C‐arm CBCT results using 6, 3, 2, and 1 scan sequences were compared to those obtained using CT. Data were compared for linear velocities of the phantom ranging from 0.6 to 1 cm/s. This covers the temporal frequencies up to 0.16 Hz corresponding to a frequency range within which 99% of the spectral energy for all temporal signals in cerebral perfusion imaging is contained.Results: The errors in measurement of temporal frequencies are mostly below 2% for all multiscan sequences. For single scan sequences, the errors increase sharply beyond 0.10 Hz. The amplitude errors increase with frequency and with decrease in the number of scans used.Conclusions:Our multiscan perfusion CT approach allows low errors in signal frequency measurement. Increasing the number of scans reduces the amplitude errors. A two‐scan sequence appears to offer the best compromise between accuracy and the associated total x‐ray and iodine dose.
Development of a flexible optical fiber based high resolution integrated PET/MRI system
Authors: Yamamoto Seiichi , Watabe Hiroshi , Kanai Yasukazu , Watabe Tadashi , Aoki Masaaki , Sugiyama Eiji , Kato Katsuhiko , Hatazawa Jun 
Published: October 2012

Purpose:The simultaneous measurement of PET and magnetic resonance imaging (MRI) is an emerging field for molecular imaging research. Although optical fiber based PET/MRI systems have advantages on less interference between PET and MRI, there is a drawback in reducing the scintillation light due to the fiber. To reduce the problem, the authors newly developed flexible optical fiber bundle based block detectors and employed them for a high resolution integrated PET/MRI system.Methods:The flexible optical fiber bundle used 0.5 mm diameter, 80 cm long double clad fibers which have dual 12 mm × 24 mm rectangular inputs and a single 24 mm × 24 mm rectangular output. In the input surface, LGSO scintillators of 0.025 mol.% (decay time: ∼31 ns: 0.9 mm × 1.3 mm × 5 mm) and 0.75 mol.% (decay time: ∼46 ns: 0.9 mm × 1.3 mm × 6 mm) were optically coupled in depth direction to form depth‐of‐interaction detector, arranged in 11 × 13 matrix and optically coupled to the fiber bundle. The two inputs of the bundle are bent for 90°, bound to one, and are optically coupled to a Hamamatsu 1‐in. square position sensitive photomultiplier tube.Results:Light loss due to the fiber bundle could be reduced and the performance of the block detectors was improved. Eight optical fiber based block detectors (16 LGSO blocks) were arranged in a 56 mm diameter ring to form a PET system. Spatial resolution and sensitivity were 1.2 mm full‐width at half‐maximum and 1.2% at the central field‐of‐view, respectively. Sensitivity change was less than 1% for 2 °C temperature changes. This PET system was integrated with a 0.3 T permanent magnet MRI system which has 17 cm diameter hole at the yoke area for insertion of the PET detector ring. There was no observable interference between PET and MRI. Simultaneous imaging of PET and MRI was successfully performed for small animal studies.Conclusions:The authors confirmed that the developed high resolution PET/MRI system is promising for molecular imaging research.
Dosimetric measurements of Onyx embolization material for stereotactic radiosurgery
Authors: Roberts Donald A. , Balter James M. , Chaudhary Neeraj , Gemmete Joseph J. , Pandey Aditya S. 
Published: October 2012

Purpose:Arteriovenous malformations are often treated with a combination of embolization and stereotactic radiosurgery. Concern has been expressed in the past regarding the dosimetric properties of materials used in embolization and the effects that the introduction of these materials into the brain may have on the quality of the radiosurgery plan. To quantify these effects, the authors have taken large volumes of Onyx 34 and Onyx 18 (ethylene‐vinyl alcohol copolymer doped with tantalum) and measured the attenuation and interface effects of these embolization materials.Methods:The manufacturer provided large cured volumes (∼28 cc) of both Onyx materials. These samples were 8.5 cm in diameter with a nominal thickness of 5 mm. The samples were placed on a block tray above a stack of solid water with an Attix chamber at a depth of 5 cm within the stack. The Attix chamber was used to measure the attenuation. These measurements were made for both 6 and 16 MV beams. Placing the sample directly on the solid water stack and varying the thickness of solid water between the sample and the Attix chamber measured the interface effects. The computed tomography (CT) numbers for bulk material were measured in a phantom using a wide bore CT scanner.Results:The transmission through the Onyx materials relative to solid water was approximately 98% and 97% for 16 and 6 MV beams, respectively. The interface effect shows an enhancement of approximately 2% and 1% downstream for 16 and 6 MV beams. CT numbers of approximately 2600–3000 were measured for both materials, which corresponded to an apparent relative electron density (RED) to water of approximately 2.7–2.9 if calculated from the commissioning data of the CT scanner.Conclusions:We performed direct measurements of attenuation and interface effects of Onyx 34 and Onyx 18 embolization materials with large samples. The introduction of embolization materials affects the dose distribution of a MV therapeutic beam, but should be of negligible consequence for effective thicknesses of less than 8 mm. The measured interface effects are also small, particularly at 6 MV. Large areas of high‐density artifacts and low‐density artifacts can cause errors in dose calculations and need to be identified and resolved during planning.
Monte Carlo performance on the x‐ray converter thickness in digital mammography using software breast models
Authors: Liaparinos P. , Bliznakova K. 
Published: October 2012

Purpose:In x‐ray mammography, some of the components that play significant role to early diagnosis are the x‐ray source, the breast composition as well as the composition of the x‐ray converter. Various studies have previously investigated separately the influence of breast characteristics and detector configuration on the optimization of mammographic imaging systems. However, it is important to examine the combined effect of both components in improving the signal transfer properties in mammography systems of the mammograms. In the present study, the authors compared and evaluated x‐ray converters using software breast models and realistic mammographic spectra in terms of: (a) zero‐frequency detective quantum efficiency (DQE) and (b) sensitivity. The impact of x‐ray converter thickness on contrast threshold (CTH) for observer assessment, based on the Rose model, was demonstrated as well.Methods:Monte Carlo techniques were applied to simulate the x‐ray interactions within the software breast phantoms and thereafter within the detective medium. Simulations involved: (a) two mammographic x‐ray spectra: 28 kV Mo, 0.030 mm Mo, and 32 kV W, 0.050 mm Rh of different entrance surface air kerma (ESAK: 3–7 mGy), (b) realistic breast models (dense and fatty) and (c) x‐ray converter materials most frequently considered in investigations on energy integrating digital mammography detectors: the Gd2O2S:Tb granular phosphor, the CsI:Tl structured phosphor, and the a‐Se photoconductive layer. Detector material thickness was considered to vary in the range from 50 mg/cm2 up to 150 mg/cm2.Results:The Monte Carlo study showed that: (a) the x‐ray beam becomes less penetrating after passing through dense breasts leading to higher values of zero‐frequency DQE of the x‐ray imaging converters and improved CTH values in all cases considered, (b) W/Rh target/filter combination results in improved CTH values at higher ESAK values, and (c) a‐Se shows higher zero‐frequency DQE values than the phosphor‐based converters, Gd2O2S:Tb and CsI:Tl. However, thicker layers of CsI:Tl could be comparable to a‐Se layers achieving approximately 27.6% CTH improvement at a thickness of 150 mg/cm2.Conclusions:The present Monte Carlo investigation indicates that in the energy range employed in mammography, an upper limit, approximately 100 mg/cm2, should be considered in the development of thicker a‐Se converters. On the other hand, above this thickness value, CsI:Tl converter could improve its imaging performance.
Role of Defective Thymic Function in Onset of Ganciclovir-Resistant Cytomegalovirus after Cord Blood Transplantation
Authors: Cantisán Sara , Martín Carmen , Romero-Sánchez María C. , Ferrando-Martínez Sara , Martínez Francisco , Rivero Antonio , Torres Antonio , Solana Rafael , Torre-Cisneros Julián 
Published: October 2012

ABSTRACT

A case of recurrent cytomegalovirus reactivations in a cytomegalovirus-seropositive woman who received allogeneic cord blood transplantation is described. Thirteen months posttransplantation, her CD3
+
T cell count was extremely low whereas natural killer cells represented 66% of her total lymphocytes. She showed defective thymic function that might contribute to the onset of valganciclovir resistance.
Expression of Tumor Necrosis Factor Alpha-Induced Protein 3 mRNA in Peripheral Blood Mononuclear Cells Negatively Correlates with Disease Severity in Psoriasis Vulgaris
Authors: Jiang Xuebing , Tian Hongqing , Fan Yuchen , Chen Jie , Song Yonghong , Wang Shurong , Zhu Faliang , Guo Chun , Zhang Lining , Shi Yongyu 
Published: October 2012

ABSTRACT

Psoriasis vulgaris is considered a chronic inflammatory disease, but its immunopathogenesis has not been well understood. The tumor necrosis factor alpha-induced protein 3 (TNFAIP3) gene functions in negative-feedback regulation of inflammation, and its single nucleotide polymorphism is associated with psoriasis. However, the relationship between the expression level of the TNFAIP3 gene in immune cells and psoriasis is not known so far. In the present study, TNFAIP3 mRNA expression levels in peripheral blood mononuclear cells from 44 patients with psoriasis vulgaris and 30 healthy controls were determined using real-time reverse transcription-PCR analysis. We found that expression of TNFAIP3 mRNA in all patients negatively correlated with the psoriatic area and severity index (PASI) (
r
= −0.5126;
P
= 0.0004) as well as with the percentage of body surface area affected by psoriasis (
r
= −0.5013;
P
= 0.0005). Patients were divided into mild and severe groups based on the mean PASI score. Expression of TNFAIP3 mRNA in the mild group was higher than that in the severe group (
P
= 0.0064). Moreover, compared with that in healthy controls, the expression of TNFAIP3 mRNA in the mild group was significantly upregulated (
P
= 0.0004), but the expression of TNFAIP3 mRNA in the severe group was not. These results suggest that the expression level of TNFAIP3 plays an important role in the pathology of psoriasis vulgaris and that the loss of upregulation of TNFAIP3 expression may contribute to the severity of psoriasis vulgaris.