bluuebunny/crossref_metadata_2025 huggingface dataset:
Rapid, in situ detection of Agrobacterium tumefaciens attachment to leaf tissue
Authors: Simmons Christopher W. , Nitin N. , VanderGheynst Jean S.
Published: July 2012

Attachment of the plant pathogen Agrobacterium tumefaciens to host plant cells is an early and necessary step in plant transformation and agroinfiltration processes. However, bacterial attachment behavior is not well understood in complex plant tissues. Here we developed an imaging‐based method to observe and quantify A. tumefaciens attached to leaf tissue in situ. Fluorescent labeling of bacteria with nucleic acid, protein, and vital dyes was investigated as a rapid alternative to generating recombinant strains expressing fluorescent proteins. Syto 16 green fluorescent nucleic acid stain was found to yield the greatest signal intensity in stained bacteria without affecting viability or infectivity. Stained bacteria retained the stain and were detectable over 72 h. To demonstrate in situ detection of attached bacteria, confocal fluorescent microscopy was used to image A. tumefaciens in sections of lettuce leaf tissue following vacuum‐infiltration with labeled bacteria. Bacterial signals were associated with plant cell surfaces, suggesting detection of bacteria attached to plant cells. Bacterial attachment to specific leaf tissues was in agreement with known leaf tissue competencies for transformation with Agrobacterium. Levels of bacteria attached to leaf cells were quantified over time post‐infiltration. Signals from stained bacteria were stable over the first 24 h following infiltration but decreased in intensity as bacteria multiplied in planta. Nucleic acid staining of A. tumefaciens followed by confocal microscopy of infected leaf tissue offers a rapid, in situ method for evaluating attachment of A. tumefaciens' to plant expression hosts and a tool to facilitate management of transient expression processes via agroinfiltration. © 2012 American Institute of Chemical Engineers Biotechnol. Prog., 2012
Engineering the acceptor specificity of trehalose phosphorylase for the production of trehalose analogs
Authors: Van der Borght Jef , Soetaert Wim , Desmet Tom
Published: July 2012

Trehalose (α‐D‐glucopyranosyl‐(1,1)‐α‐D‐glucopyranoside) is widely used in the food industry, thanks to its protective effect against freezing and dehydration. Analogs of trehalose have the additional benefit that they are not digested and thus do not contribute to our caloric intake. Such trehalose analogs can be produced with the enzyme trehalose phosphorylase, when it is applied in the reverse, synthetic mode. Despite the enzyme's broad acceptor specificity, its catalytic efficiency for alternative monosaccharides is much lower than for glucose. For galactose, this difference is shown here to be caused by a lower Km whereas the kcat for both substrates is equal. Consequently, increasing the affinity was attempted by enzyme engineering of the trehalose phosphorylase from Thermoanaerobacter brockii, using both semirational and random mutagenesis. While a semirational approach proved unsuccessful, high‐throughput screening of an error‐prone PCR library resulted in the discovery of three beneficial mutations that lowered Km two‐ to three‐fold. In addition, it was found that mutation of these positions also leads to an improved catalytic efficiency for mannose and fructose, suggesting their involvement in acceptor promiscuity. Combining the beneficial mutations did not further improve the affinity, and even resulted in a decreased catalytic activity and thermostability. Therefore, enzyme variant R448S is proposed as new biocatalyst for the industrial production of lactotrehalose (α‐D‐glucopyranosyl‐(1,1)‐α‐D‐galactopyranoside). © 2012 American Institute of Chemical Engineers Biotechnol. Prog., 2012
A mouse neurodegenerative dynein heavy chain mutation alters dynein motility and localization in Neurospora crassa
Authors: Sivagurunathan Senthilkumar , Schnittker Robert R. , Nandini Swaran , Plamann Michael D. , King Stephen J.
Published: July 2012

Cytoplasmic dynein is responsible for the transport and delivery of cargoes in organisms ranging from humans to fungi. Dysfunction of dynein motor machinery due to mutations in dynein or its activating complex dynactin can result in one of several neurological diseases in mammals. The mouse Legs at odd angles (Loa) mutation in the tail domain of the dynein heavy chain has been shown to lead to progressive neurodegeneration in mice. The mechanism by which the Loa mutation affects dynein function is just beginning to be understood. In this work, we generated the dynein tail mutation observed in Loa mice into the Neurospora crassa genome and utilized cell biological and complementing biochemical approaches to characterize how that tail mutation affected dynein function. We determined that the Loa mutation exhibits several subtle defects upon dynein function in N. crassa that were not seen in mice, including alterations in dynein localization, impaired velocity of vesicle transport, and in the biochemical properties of purified motors. Our work provides new information on the role of the tail domain on dynein function and points out areas of future research that will be of interest to pursue in mammalian systems. © 2012 Wiley Periodicals, Inc.
EU sampling strategies for the detection of veterinary drug residues in aquaculture species: Are they working?
Authors: Morris D. J. , Gray A. J. , Kay J. F. , Gettinby G.
Published: July 2012

Over the past 50 years, the culture of aquatic species in controlled conditions to enhance production has grown in importance and now provides nearly 50% of the world's seafood supply. In part, this expansion has been made possible by the use of antibiotics, antifungals, and other veterinary medicines to control disease and improve welfare. Despite guidelines being available, the sampling programmes for drug residue surveillance of aquaculture products recommended by the CODEX Alimentarius Commission were withdrawn in 2008 and put under review. Directive 96/23/EC sets out legislation to govern how sampling programmes for drug residue surveillance should be conducted within the EU. This directive applies both to produce raised within the EU and also imported products from third countries. This communication examines the existing EU sampling regimen for aquaculture products and comments on its possible application in a global context. We examine UK statutory sampling data that, while indicating the effectiveness of the directive, also suggests that the directive may lead to unnecessary sampling. Regarding imports, examination of the Rapid Alert System for Food and Feed (RASFF) database using process control charts and statistical modelling suggests that the sampling regimen described in the directive is effective but not sufficiently flexible for the range of aquaculture practices that exist. Limitations of the directive, datasets, and practices are further discussed. © 2012 John Wiley & Sons, Ltd.
Combining ISO/IEC 17025:2005 and European Commission Decision 2002/657 audit requirements: A practical way forward
Authors: Kay Jack F.
Published: July 2012

Laboratories involved in the analyses of veterinary drug residues are under increasing pressure to demonstrate that they produce meaningful and reliable data. Quality assurance and quality control systems are implemented in laboratories to provide evidence of this and these are subject to external assessment to ensure that they are effective.

Audits to ISO/IEC 17025:2005, an internationally accepted standard, and subsequent accreditation provide laboratories and their customers with a degree of assurance that the laboratories are operating in control and the data they report can be relied on. However, national or regional authorities may place additional requirements on laboratories to ensure quality data are reported. For example, in the European Union, all official control laboratories involved in veterinary drug residue analyses must also meet the requirements of European Commission Decision 2002/657/EC which sets performance criteria for analytical methods used in this area and these are subject to additional audits by national or regional authorities.

All audits place considerable time and resource demands on laboratories and this paper discusses the burden audits place on laboratories and describes a UK initiative to combine these audits to the benefit of both the regulatory authority and the laboratory. © 2012 John Wiley & Sons, Ltd.
The role of pharmacokinetics in veterinary drug residues
Authors: Lees Peter , Toutain Pierre‐Louis
Published: July 2012

This review provides a summary of those pharmacokinetic properties of veterinary drugs relevant to marker residues, marker tissues, and residue depletion rates. The scientific literature in this field is very extensive and there is also a wealth of data available on the websites of various regulatory jurisdictions. Therefore, this review is limited to selected examples, cited to illustrate general principles. The areas considered are: (1) the relationship of dose to plasma concentration through the pharmacokinetic properties, area under plasma concentration‐time curve, bioavailability, and clearance; (2) the critical dependence of drug pharmacokinetics and residue depletion on product formulation; (3) disease state and population pharmacokinetics; and (4) the requirement for residue depletion studies for generic products shown to be bioequivalent to pioneer products. © 2012 John Wiley & Sons, Ltd.
The physiological way: Monitoring RNA expression changes as new approach to combat illegal growth promoter application
Authors: Riedmaier Irmgard , Pfaffl Michael W. , Meyer Heinrich H. D.
Published: July 2012

The use of growth‐promoting agents in food‐producing animals is forbidden in the European Union (EU). Therefore a strict control programme has been developed, detecting residues of all known growth‐promoting agents using chromatographical methods in combination with mass spectrometry or immunoassays. New designed xenobiotic substances or hormone cocktails are difficult to identify with these methods and therefore the development of new sensitive test methods is important.

A promising indirect approach is the detection of physiological effects of the administered growth promoters on the molecular level using ‘omic’ technologies. The analysis of the transcriptome on mRNA and miRNA level and thereby identifying biomarkers for the use of anabolic agents is one possible strategy for developing a new screening method. This paper describes the technologies available for gene expression profiling and summarizes the efforts made in the analysis of the transcriptome in order to identify potential gene expression biomarkers for the use of growth promoters in cattle. © 2012 John Wiley & Sons, Ltd.
Complex Formation of Calcium Bis(tetraethylaluminate) with N‐Donor Ligands
Authors: Hülsmann Matthias , Neumann Beate , Stammler Hans‐Georg , Mitzel Norbert W.
Published: July 2012

Treatment of calcium bis(tetraethylaluminate) with the bidentate N‐donor ligands tetramethylmethylenediamine (L = TMMDA), tetramethylethylenediamine (L = TMEDA) and N,N′‐dimethylpiperazine (L = DMP) and the tridentate N‐donor ligands 1,3,5‐trialkyl‐1,3,5‐triazacyclohexane {L = cyclo‐[N(R)CH2]3, R = Me (TMTAC), Cy (TCyTAC), tBu (TtBuTAC)} resulted in the formation of complexes of the formulae [Ca(AlEt4)2L]. These compounds were characterised by NMR spectroscopy and elemental analyses. Single crystals suitable for X‐ray diffraction experiments were obtained from the TMMDA, DMP, TCyTAC and TMTAC complexes. In the case of TMTAC, the complex crystallises with two TMTAC ligands bonded to the Ca atom, [Ca(AlEt4)2(TMTAC)2], but in solution only one TMTAC ligand is bonded to the Ca atom. NMR spectroscopy at various temperatures shows the tetraethylaluminate units to be dynamically bonded in these compounds (i.e., they are found to be partially dissociated). This dynamic bonding situation avoids steric overcrowding and – unlike related rare‐earth metal compounds – this behaviour inhibits further degradation reactions. The reaction of calcium bis(tetraethylaluminate) with the NH‐functional diisopropylamine leads to its deprotonation and results in the formation of a dimeric calcium amide [(η2‐AlEt4)2Ca(μ‐NiPr2)2Ca(η2‐AlEt4)2]. This compound was characterised by single‐crystal X‐ray diffraction, NMR spectroscopy and elemental analyses.
Copper‐Catalyzed Decarboxylative Three‐Component Reactions for the Synthesis of Imidazo[1,2‐a]pyridines
Authors: Palani Thiruvengadam , Park Kyungho , Kumar Manian Rajesh , Jung Hyun Ming , Lee Sunwoo
Published: July 2012

Imidazo[1,2‐a]pyridine derivatives were synthesized through multicomponent coupling reactions of 2‐aminopyridines, aldehydes, and alkynecarboxylic acids in the presence of 10 mol‐% CuI/Cu(OTf)2. Both aryl‐ and alkyl‐substituted alkynecarboxylic acids, including propiolic acid, were good alkyne sources and afforded the desired imidazo[1,2‐a]pyridines in good yields through the decarboxylative coupling reactions. Arylalkynecarboxylic acids were synthesized through palladium‐catalyzed coupling reactions between aryl iodides and propiolic acid and reacted with 2‐aminopyridine and aldehydes, with or without a purification step. In both cases the desired imidazo[1,2‐a]pyridines were obtained in good yields. Mechanistic studies suggested that in the case of propiolic acid the decarboxylative addition predominates over terminal alkyne addition.
Capillary gel electrophoresis for precise protein quantitation
Authors: Cianciulli Claudia , Hahne Thomas , Wätzig Hermann
Published: July 2012

CGE, also known as SDS‐CGE, is being established in the pharmaceutical industry replacing SDS‐PAGE. In most cases, the method is applied for the identity and purity control of proteins, for example monoclonal antibodies. In order to quantify these components with sufficient precision using the same quality control method, a RSD for the quantitative analysis under 2% is required. A reliable and highly precise CGE method could be obtained after thorough optimization. It was crucial to increase the sample concentration and the injection volume in order to achieve sufficiently high S/N ratios (>70). The application of hydrodynamic injection is beneficial for the precision of the method compared to the traditionally used electrokinetic one. Linearity was demonstrated and LOD and LOQ were estimated. Both injection modes were compared in long series runs (n = 48). Furthermore, the use of an internal standard was investigated. Thus, the RSD% of the migration time was reduced from 0.9 to 0.2% and the RSD% of peak areas was greatly improved. However, the normalization to the total area further reduced the influence of the injection error. RSD% for the peak area ratios of typically between 1 and 2% was provided.
Determination of hydroxy acids in cosmetics by chemometric experimental design and cyclodextrin‐modified capillary electrophoresis
Authors: Liu Pei‐Yu , Lin Yi‐Hui , Feng Chia Hsien , Chen Yen‐Ling
Published: July 2012

A CD‐modified CE method was established for quantitative determination of seven hydroxy acids in cosmetic products. This method involved chemometric experimental design aspects, including fractional factorial design and central composite design. Chemometric experimental design was used to enhance the method's separation capability and to explore the interactions between parameters. Compared to the traditional investigation that uses multiple parameters, the method that used chemometric experimental design was less time‐consuming and lower in cost. In this study, the influences of three experimental variables (phosphate concentration, surfactant concentration, and methanol percentage) on the experimental response were investigated by applying a chromatographic resolution statistic function. The optimized conditions were as follows: a running buffer of 150 mM phosphate solution (pH 7) containing 0.5 mM CTAB, 3 mM γ‐CD, and 25% methanol; 20 s sample injection at 0.5 psi; a separation voltage of −15 kV; temperature was set at 25°C; and UV detection at 200 nm. The seven hydroxy acids were well separated in less than 10 min. The LOD (S/N = 3) was 625 nM for both salicylic acid and mandelic acid. The correlation coefficient of the regression curve was greater than 0.998. The RSD and relative error values were all less than 9.21%. After optimization and validation, this simple and rapid analysis method was considered to be established and was successfully applied to several commercial cosmetic products.
A photonic‐microfluidic integrated device for reliable fluorescence detection and counting
Authors: Watts Benjamin R. , Zhang Zhiyi , Xu Chang Qing , Cao Xudong , Lin Min
Published: July 2012

A photonic‐microfluidic integrated device is demonstrated with excellent and reliable fluorescence detection performance. CV values of 8% for 2.5‐μm beads and 14% for 6‐μm beads were achieved through the correct deployment of carefully formed excitation beam shapes via integrated on‐chip optics even without the use of 3D hydrodynamic focusing or a high‐quality laser source and single mode beam propagation. The devices are fabricated in a monolithic planar fashion using a system of microlenses and waveguides integrated with microfluidic channels on‐chip and packaged using a high‐quality and low‐cost channel sealing and high‐performance interconnecting technology developed from our earlier works. Beam geometry in the excitation region is shown to affect the variation of fluorescence intensity from specimens, hence configurations of beam geometry targeted for a specific bead sizes are examined to ensure proper deployment of the lens designs. The formed high‐quality optical excitation regions ensure reliable detection even with relaxed hydrodynamic focusing to ensure applicability with multiple specimen sizes. Device performance with each bead size was found to be acceptable for a range of beam geometries with a different ideal configuration for each bead size. These device designs help to form a device that will supplement conventional flow cytometry in point‐of‐care and remote detection applications by performing specific detections with an inexpensive and replaceable device.
Stuffer‐free multiplex ligation‐dependent probe amplification based on conformation‐sensitive capillary electrophoresis: A novel technology for robust multiplex determination of copy number variation
Authors: Shin Gi Won , Jung Seung‐Hyun , Yim Seon‐Hee , Chung Boram , Yeol Jung Gyoo , Chung Yeun‐Jun
Published: July 2012

Developing diagnostic tools based on the application of known disease/phenotype‐associated copy number variations (CNVs) requires the capacity to measure CNVs in a multiplex format with sufficient reliability and methodological simplicity. In this study, we developed a reliable and user‐friendly multiplex CNV detection method, termed stuffer‐free MLPA‐CE‐SSCP, that combines a variation of multiplex ligation‐dependent probe amplification (MLPA) with CE‐SSCP. In this variation, MLPA probes were designed without the conventionally required stuffer sequences. To separate the similar‐sized stuffer‐free MLPA products, we adopted CE‐SSCP rather than length‐dependent conventional CE analysis. An examination of the genomic DNA from five cell lines known to vary in X‐chromosome copy number (1–5) revealed that copy number determinations using stuffer‐free MLPA‐CE‐SSCP were more accurate than those of conventional MLPA, and the CV of the measured copy numbers was significantly lower. Applying our system to measure the CNVs on autosomes between two HapMap individuals, we found that all peaks for CNV targets showed the expected copy number changes. Taken together, our results indicate that this new strategy can overcome the limitations of conventional MLPA, which are mainly related to long probe length and difficulties of probe preparation.
Biomagnification of polychlorinated biphenyls in a harbor seal (Phoca vitulina) food web from the strait of Georgia, British Columbia, Canada
Authors: Cullon Donna L. , Yunker Mark B. , Christensen Jennie R. , Macdonald Robie W. , Whiticar Michael J. , Dangerfield Neil J. , Ross Peter S.
Published: July 2012

Polychlorinated biphenyl (PCB) biomagnification was characterized in a harbor seal food web in the Strait of Georgia, British Columbia, Canada. Trophic magnification factors (TMFs) for PCBs averaged 3.6, with a range of 0.7 to 9.4. The TMFs for individual congeners correlated with log KOW (r2 = 0.56, p < 0.001), reflecting the role that physicochemical properties play in driving the biomagnification of PCBs in marine food webs. However, TMFs differed among PCB structure activity groups, clearly indicating an additional role for metabolic transformation of certain PCBs. The known feeding preferences of harbor seals enabled the calculation of trophic level-adjusted biomagnification factors (BMFTL) for PCBs in this species, which averaged 13.4 and ranged from 0.2 to 150.6. Metabolic transformation in seals explained some of the variation in congener-specific biomagnification, with lower BMFTL values for PCB congeners with meta- and parachlorine unsubstituted positions. Principal components analysis revealed the distinct roles played by trophic level, log KOW, and metabolic transformation in explaining the notable differences in PCB patterns among harbor seals, their pups, and their prey. In the present study, the authors estimate there to be approximately 76 kg of PCBs in the biota of the Strait of Georgia, of which 1.6 kg is retained by harbor seals. Environ. Toxicol. Chem. 2012; 31: 2445–2455. © 2012 SETAC
Pathogenic infection confounds induction of the estrogenic biomarker vitellogenin in rainbow trout
Authors: Burki Richard , Krasnov Aleksei , Bettge Kathrin , Rexroad Caird E. , Afanasyev Sergej , Antikainen Mia , Burkhardt-Holm Patricia , Wahli Thomas , Segner Helmut
Published: July 2012

To examine the behavior of the estrogenic biomarker vitellogenin (VTG) under the combined impact of estrogens and pathogens, parasite-infected or noninfected rainbow trout were exposed to two doses of 17β-estradiol (E2). Infected and E2-exposed fish showed significantly lower hepatic VTG mRNA levels than healthy fish. Transcriptome data suggest that this was due to energetic constraints. Reduced responsiveness of the VTG biomarker in parasitized fish might obscure detection of low-level field exposure. Environ. Toxicol. Chem. 2012; 31: 2318–2323. © 2012 SETAC
Elevated methylation of HPV16 DNA is associated with the development of high grade cervical intraepithelial neoplasia
Authors: Mirabello Lisa , Schiffman Mark , Ghosh Arpita , Rodriguez Ana C. , Vasiljevic Natasa , Wentzensen Nicolas , Herrero Rolando , Hildesheim Allan , Wacholder Sholom , Scibior‐Bentkowska Dorota , Burk Robert D. , Lorincz Attila T.
Published: July 2012

We explored the association of human papillomavirus type 16 (HPV16) DNA methylation with age, viral load, viral persistence and risk of incident and prevalent high grade CIN (CIN2+) in serially collected specimens from the Guanacaste, Costa Rica cohort. 273 exfoliated cervical cell specimens (diagnostic and pre‐diagnostic) were selected: (1) 92 with HPV16 DNA clearance (controls), (2) 72 with HPV16 DNA persistence (without CIN2+) and (3) 109 with CIN2+. DNA was extracted, bisulfite converted and methylation was quantified using pyrosequencing assays at 66 CpGs across the HPV genome. The Kruskal‐Wallis test was used to determine significant differences among groups, and receiver operating characteristic curve analyses were used to evaluate how well methylation identified women with CIN2+. In diagnostic specimens, 88% of CpG sites had significantly higher methylation levels in CIN2+ after correction for multiple tests compared with controls. The highest area under the ROC curve (AUC) was 0.82 for CpG site 6457 in L1, and a diagnostic sensitivity of 91% corresponded to a specificity of 60% for CIN2+. Prospectively, 17% of CpG sites had significantly higher methylation in pre‐diagnostic CIN2+ specimens (median time of 3 years before diagnosis) versus controls. The strongest pre‐diagnostic CpG site was 6367 in L1 with an AUC of 0.76. Age‐stratified analyses suggested that women older than the median age of 28 years have an increased risk of precancer associated with high methylation. Higher methylation in CIN2+ cases was not explained by higher viral load. We conclude that elevated levels of HPV16 DNA methylation may be useful to predict concurrently diagnosed as well as future CIN2+.
20(S)‐protopanaxadiol‐aglycone downregulation of the full‐length and splice variants of androgen receptor
Authors: Cao Bo , Liu Xichun , Li Jing , Liu Shuang , Qi Yanfeng , Xiong Zhenggang , Zhang Allen , Wiese Thomas , Fu Xueqi , Gu Jingkai , Rennie Paul S. , Sartor Oliver , Lee Benjamin R. , Ip Clement , Zhao Lijuan , Zhang Haitao , Dong Yan
Published: July 2012

As a public health problem, prostate cancer engenders huge economic and life‐quality burden. Developing effective chemopreventive regimens to alleviate the burden remains a major challenge. Androgen signaling is vital to the development and progression of prostate cancer. Targeting androgen signaling via blocking the production of the potent ligand dihydrotestosterone has been shown to decrease prostate cancer incidence. However, the potential of increasing the incidence of high‐grade prostate cancers has been a concern. Mechanisms of disease progression after the intervention may include increased expression of androgen receptor (AR) in prostate tissue and expression of the constitutively active AR splice variants (AR‐Vs) lacking the ligand‐binding domain. Thus, novel agents targeting the receptor, preferentially both the full‐length and AR‐Vs, are urgently needed. In the present study, we show that ginsenoside 20(S)‐protopanaxadiol‐aglycone (PPD) effectively downregulates the expression and activity of both the full‐length AR and AR‐Vs. The effects of PPD on AR and AR‐Vs are manifested by an immediate drop in proteins followed by a reduction in transcripts, attributed to PPD induction of proteasome‐mediated degradation and inhibition of the transcription of the AR gene. We further show that although PPD inhibits the growth as well as AR expression and activity in LNCaP xenograft tumors, the morphology and AR expression in normal prostates are not affected. This study is the first to show that PPD suppresses androgen signaling through downregulating both the full‐length AR and AR‐Vs, and provides strong rationale for further developing PPD as a promising agent for the prevention and/or treatment of prostate cancer.
Interplay between protein‐modified surface and functional response of osteoblasts
Authors: Chaudhary P. , Pesacreta T. C. , Misra R. D. K.
Published: July 2012

The objective of the study is to elucidate the interplay between fibronectin‐metal hybrid surfaces and osteoblast function. The practical relevance is that a significant initial step in the process of prosthetic integration within a physiological system is the rapid adsorption of proteins, including fibronectin, on the surface of biomedical device. Here, we compare and contrast the cell–substrate interactions on bare and protein‐modified surfaces. The protein adsorption on the surface was beneficial in favorably modulating biological functions including cell attachment, proliferation, and viability. Additionally, immunofluorescence studies demonstrated stronger vinculin signals associated with actin stress fibers in the outer regions of the cells and cellular extensions on protein‐adsorbed surfaces. These results support the hypothesis that protein adsorption on artificial biomedical devices can promote bioactivity and regulate biological functions. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 100A:3157–3166, 2012.
In vitro antibacterial evaluation of sol–gel‐derived Zn‐, Ag‐, and (Zn + Ag)‐doped hydroxyapatite coatings against methicillin‐resistant Staphylococcus aureus
Authors: Samani S. , Hossainalipour S. M. , Tamizifar M. , Rezaie H. R.
Published: July 2012

Hydroxyapatite (HAp) coatings were applied using sol–gel method. Phosphor pentoxide and calcium nitrate were used as phosphorous and calcium precursors, respectively. Zinc nitrate and silver nitrate were used as substitute of calcium in HAp structure. As a base concentration, 1.5 wt %Ag and 2.5 wt %Zn were used. The weight percent of Ag was increased at 0.3 wt% and Zn content was scaled down at 0.5 wt%. Phase analysis and chemical bonds of synthesized materials were studied by XRD and FTIR. Antibacterial activity of Ag‐ and Zn‐doped samples against methicilin‐resistant Staphylococcus aureus (MRSA) were assessed by the plate‐counting method. The XRD and FTIR results proved formation of HAp compound. Colony counting showed that silver and zinc ions prevent proliferation and growth of MRSA. Interestingly, co‐presence of metal ions improves the antibacterial effectiveness of the coatings and the combined effect was greater than sum of the individual effects when each was administered alone. Overall, synergism between antibacterial activities of Zn2+ and Ag+ ions against MRSA can be suggested. Thus, cell toxicity decreases and biocompatibility increases without any decrement in antibacterial activity. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 101A:222–230, 2013.
Ultrashort echo time MR imaging with off‐resonance saturation for characterization of pathologically altered Achilles tendons at 3 T
Authors: Grosse Ulrich , Syha Roland , Martirosian Petros , Wuerslin Christian , Horger Marius , Grözinger Gerd , Schick Fritz , Springer Fabian
Published: July 2012

Off‐resonance radiofrequency saturation pulses applied prior to regular excitation in MR sequences can be used to modify signal contrast based on magnetization transfer and direct saturation effects. Clinical applicability and value of ultrashort echo time sequences combined with off‐resonance saturation pulses was tested in 16 healthy and 14 tendinopathic as well as paratendinopathic Achilles tendons in vivo at 3 T. A 3D ultrashort echo time sequence in combination with a gaussian off‐resonance saturation pulse (frequency offset: 1000–5000 Hz) was used to modify the detectable MR signal intensity from the Achilles tendon. Off‐resonance saturation ratio was calculated as the relative reduction in signal intensity under selective off‐resonance saturation in relation to a reference measurement without any saturation pulse. Off‐resonance saturation ratio in tendons of healthy volunteers ranged from 0.52 ± 0.06 (1000 Hz) to 0.24 ± 0.02 (5000 Hz), whereas symptomatic tendinopathic tendons (0.35 ± 0.04 to 0.17 ± 0.02) and asymptomatic tendinopathic tendons (0.41 ± 0.06 to 0.21 ± 0.02) showed significantly lower mean off‐resonance saturation ratio values. Off‐resonance saturation ratio values might provide a sensitive and quantitative marker for assessment of pathological microstructure alterations of the Achilles tendon. Magn Reson Med, 2013. © 2012 Wiley Periodicals, Inc.
Increasing signal homogeneity and image quality in abdominal imaging at 3 T with very high permittivity materials
Authors: de Heer P. , Brink W. M. , Kooij B. J. , Webb A. G.
Published: July 2012

The appearance of severe signal drop‐outs in abdominal imaging at 3 T arises primarily from areas of very low B transmit field in the body, and is problematic in both obese as well as very thin subjects. In this study, we show how thin patient‐friendly pads containing new high permittivity materials can be designed and optimized, and when placed around the subject increase substantially the B uniformity and the image quality. Results from nine healthy volunteers show that inclusion of these dielectric pads results in statistically significant decreases in the coefficient of variance of the B field, with stronger and more uniform fields being produced. In addition there are statistically significant decreases in time‐averaged power required for scanning. These differences are present in both quadrature‐mode operation (coefficient of variance decrease, P < 0.0001, mean 25.4 ± 10%: power decrease, P = 0.005, mean 14 ± 14%) and also for the RF‐shimmed case (coefficient of variance decrease, P = 0.01, mean 16 ± 13%: power decrease, P = 0.005, mean 22 ± 11%) of a dual‐transmit system. Magn Reson Med, 2012. © 2012 Wiley Periodicals, Inc.
A phase field model of dynamic fracture: Robust field updates for the analysis of complex crack patterns
Authors: Hofacker M. , Miehe C.
Published: July 2012

The numerical modeling of dynamic failure mechanisms in solids due to fracture based on sharp crack discontinuities suffers in situations with complex crack topologies and demands the formulation of additional branching criteria. This drawback can be overcome by a diffusive crack modeling, which is based on the introduction of a crack phase field. Following our recent works on quasi‐static modeling of phase‐field‐type brittle fracture, we propose in this paper a computational framework for diffusive fracture for dynamic problems that allows the simulation of complex evolving crack topologies. It is based on the introduction of a local history field that contains a maximum reference energy obtained in the deformation history, which may be considered as a measure of the maximum tensile strain in the history. This local variable drives the evolution of the crack phase field. Its introduction provides a very transparent representation of the balance equation that governs the diffusive crack topology. In particular, it allows for the construction of a very robust algorithmic treatment for elastodynamic problems of diffusive fracture. Here, we extend the recently proposed operator split scheme from quasi‐static to dynamic problems. In a typical time step, it successively updates the history field, the crack phase field, and finally the displacement field. We demonstrate the performance of the phase field formulation of fracture by means of representative numerical examples, which show the evolution of complex crack patterns under dynamic loading. Copyright © 2012 John Wiley & Sons, Ltd.
A novel hyperbranched polyborazine and its reactive blend with benzoxazine thermosets
Authors: Liu Yuhong , Zhang Xiying , Yang Xin
Published: July 2012

Boron carbonitride polymers have been arising abiding interest due to their excellent thermal and mechanical properties. In this study, a novel kind of hyperbranched polymer based on boron carbonitride skeleton, polyborazine, has been synthesized by a convenient A2+B3 approach. The chemical structure of polyborazine was confirmed by Fourier‐transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR), X‐ray photoelectron spectroscopy (XPS), and size exclusion chromatography (SEC). FT‐IR and X‐ray diffraction (XRD) pattern exhibited that the boron carbonitride compound formed during the pyrolysis process contributed to the improved thermal property of polyborazine. Nevertheless, the polyborazine can catalyze the cure process of benzoxazine thermosets, and enhance the thermal stability of benzoxazine thermosets owning to the presence of the preceramic compound. The approach for fabricating reactive ceramic precursor polymer with prepolymer blend system reveals promising results for thermosets that demanding remarkable thermal stability and oxidation resistance. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers
Electrochemical oxidation of ionic liquids at highly boron doped diamond electrodes
Authors: Fabiańska Aleksandra , Ossowski Tadeusz , Bogdanowicz Robert , Czupryniak Justyna , Gnyba Marcin , Odzga Tomasz , Janssens Stoffel D. , Haenen Ken , Siedlecka Ewa M.
Published: July 2012

An electrochemical oxidation using a highly boron‐doped diamond (BDD) electrode has been tested for the treatment of solutions containing ionic liquids (ILs). The double‐sided Si/highly BDD electrodes were synthesized by microwave plasma enhanced chemical vapour deposition (MW PE CVD). Investigation of the electrode surface with scanning electron microscopy (SEM) confirmed that the synthesized layers were continuous and formed densely packed grain structure. The structure of BDD was confirmed by Raman spectra analysis. The effect of IL structure as the kind of electrolyte (Na2SO4 and NaCl) has been investigated. Electrolyses were conducted in an undivided electrolytic cell under galvanostatic conditions. The efficiency of the process has been evaluated in terms of variations of IL concentrations and chemical oxygen demand (COD) removal. Results show that pyridinium ILs were easier removed than imidazolium salts. The intermediates of electrochemical degradation of 1‐butyl‐3‐methylimidazolium salt were detected, and IL degradation pathway was proposed based on the analytical results. It was suggested that •OH radicals produced by water electrolysis attacked IL to form its derivatives with keto groups substituted to imidazolium ring. These compounds underwent ring breakage, which led to the formation of aliphatic acids that were eventually mineralized by electrolysis to CO2. Other by‐products were obtained by cutting one of the side chains substituted to N atoms in imidazolium ring. Additionally in NaCl electrolyte chloroorganic by‐products were identified.
Cryopreservation of Parathyroid Tissue after Parathyroid Surgery for Renal Hyperparathyroidism: Does it Really Make Sense?
Authors: Schneider Ralph , Ramaswamy Annette , Slater Emily P. , Bartsch Detlef K. , Schlosser Katja
Published: July 2012

Background

Metachronous autotransplantation of cryopreserved parathyroid tissue is a technique for treating postoperative hypoparathyroidism after parathyroid surgery for renal hyperparathyroidism (rHPT). The aim of the present study was to evaluate our institution’s experience with metachronous autotransplantation to analyze the role of cryopreservation in the treatment of rHPT and to determine for whom and when cryopreservation of parathyroid tissue should be deemed necessary.

Methods

A prospective database of patients with rHPT who underwent surgery between 1976 and 2011 was screened for patients with hypoparathyroidism who received a metachronous autotransplantation. Data were analyzed regarding clinical data, histopathological findings of the cryopreserved parathyroid tissues, and patient outcome after metachronous replantation of parathyroid tissue.

Results

Fifteen of 883 patients with rHPT underwent a metachronous autotransplantation under local anesthesia at a mean time of 23 months following the last cervical surgery. Histopathology of the parathyroid tissue chosen for transplantation revealed a necrosis rate of 0 % in 14 and 70 % in one patient. Mean preoperative serum calcium and parathyroid hormone (PTH) levels were 2.0 mmol/l and 3.7 pg/ml, respectively. Autotransplantation raised mean serum calcium and PTH levels to 2.2 mmol/l and 97.5 pg/ml, respectively, after a mean follow‐up of 78 months.

Conclusions

Metachronous autotransplantation following parathyroid surgery in patients with rHPT effectively normalizes PTH and calcium levels. The success rate is high if an adequate cryopreservation procedure is applied. However, it is rarely necessary, and therefore the cryopreservation of parathyroid tissue in all patients has to be questioned, at least from an economic point of view.
Synthesis of methyl ketones by metabolically engineered Escherichia coli
Authors: Park John , Rodríguez-Moyá María , Li Mai , Pichersky Eran , San Ka-Yiu , Gonzalez Ramon
Published: July 2012

Methyl ketones are a group of highly reduced platform chemicals with widespread applications in the fragrance, flavor and pharmacological industries. Current methods for the industrial production of methyl ketones include oxidation of hydrocarbons, but recent advances in the characterization of methyl ketone synthases from wild tomato have sparked interest towards the development of microbial platforms for the industrial production of methyl ketones. A functional methyl ketone biosynthetic pathway was constructed in Escherichia coli by over-expressing two genes from Solanum habrochaites: shmks2, encoding a 3-ketoacyl-ACP thioesterase, and shmks1, encoding a beta-decarboxylase. These enzymes enabled methyl ketone synthesis from 3-ketoacyl-ACP, an intermediate in the fatty acid biosynthetic cycle. The production of 2-nonanone, 2-undecanone, and 2-tridecanone by MG1655 pTH-shmks2-shmks1 was initially detected by nuclear magnetic resonance and gas chromatography–mass spectrometry analyses at levels close to 6 mg/L. The deletion of major fermentative pathways leading to ethanol (adhE), lactate (ldhA), and acetate (pta, poxB) production allowed for the carbon flux to be redirected towards methyl ketone production, doubling total methyl ketone concentration. Variations in methyl ketone production observed under different working volumes in flask experiments led to a more detailed analysis of the effects of oxygen availability on methyl ketone concentration in order to determine optimal levels of oxygen. The methyl ketone concentration achieved with MG1655 ∆adhE ∆ldhA ∆poxB ∆pta pTrcHis2A-shmks2-shmks1, the best performer strain in this study, was approximately 500 mg/L, the highest reported for an engineered microorganism. Through the establishment of optimal operating conditions and by executing rational metabolic engineering strategies, we were able to increase methyl ketone concentrations by almost 75-fold from the initial confirmatory levels.
Logique, probabilité et rhétorique dans L'argumentation juridique
Authors: Palermo Angela
Published: July 2012

Contre la thèse qui réduit le raisonnement juridique à une simple rhétorique, l’article entend montrer que ce raisonnement répond à une exigence de vérité. Une telle démonstration exige de repenser la relation entre logique et rhétorique dans le champ juridique. La logique ici mobilisée est une logique de la probabilité, appropriée à la rationalité pragmatique. C’est du même coup la relation entre logique juridique et logique probabiliste qui se trouve interrogée, d’une part dans une perspective historique, d’autre part en tenant compte des études contemporaines sur le sujet.
Africa: Continent of genome contrasts with implications for biomedical research and health
Authors: Ramsay Michèle
Published: July 2012

The genomic architecture of African populations is poorly understood and there is considerable variation between ethno‐linguistic groups. Genome‐wide approaches have been extensively applied to search for genetic associations to complex traits in Europeans, but rarely in Africans. This is largely attributed to lower levels of funding, poor infrastructure and public health systems, and to the small pool of trained scientists. High levels of genetic variation and underlying population structure in Africans present significant challenges, but lower levels of linkage disequilibrium provide an opportunity for more effective localisation of causal variants. High throughput technologies, including dense genotyping arrays, genome sequencing and epigenome studies, together with plummeting costs, are making research more affordable, even for African scientists. Understanding the interactions between genome structure and environmental influences is essential to interpreting their contributions to the increase in infectious diseases and non‐communicable diseases, exacerbated by adverse environments and lifestyle choices. The unique genome dynamics in African populations have an important role to play in understanding human health and susceptibility to disease.
Transglutaminase‐mediated transamidation of serotonin, dopamine and noradrenaline to fibronectin: Evidence for a general mechanism of monoaminylation
Authors: Hummerich René , Thumfart Jörg-Oliver , Findeisen Peter , Bartsch Dusan , Schloss Patrick
Published: July 2012

The activity of some small GTPases is regulated by covalent transamidation of serotonin (5‐hydropxytryptamien) to glutamine residues of the enzymes. This process is mediated by transglutaminase (TGase) and is termed “serotonylation”. In addition, serotonylation of neural proteins and proteins of the extracellular matrix such as fibronectin has been demonstrated. Here we show that the catecholamines dopamine (DA) and noradrenaline (NA) inhibit serotonylation of fibronectin and that DA and NA themselves can be selectively transamidated into fibronectin by TGase. All three biogenic monoamines also block TGase‐mediated transamidation of another monoamine, monodansylacadaverine, into fibronectin, suggesting a general mechanism of TGase‐mediated “monoaminylation”.
Cytoplasmic translocation of p21 mediates NUPR1‐induced chemoresistance
Authors: Vincent Andrew J. , Ren Suping , Harris Lillianne G. , Devine Daniel J. , Samant Rajeev S. , Fodstad Oystein , Shevde Lalita A.
Published: July 2012

The expression of Nuclear Protein 1 (NUPR1) is associated with chemoresistance in multiple malignancies. We previously reported that NUPR1 functions as a transcriptional cofactor for the p300–p53 complex and transcriptionally regulates p21 expression. In the present study we investigated the activity of NUPR1 in p53‐deficient, triple‐negative, inflammatory SUM159 breast cancer cells. Our studies reveal that NUPR1 confers growth benefit and chemoresistance by causing Akt‐mediated phosphorylation and subsequent cytoplasmic re‐localization of p21 and activation of the anti‐apoptotic Bcl‐xL protein. Our findings elucidate a NUPR1‐PI‐3‐K/Akt‐phospho‐p21 axis that functions in p53‐negative, inflammatory breast cancer cells to enhance chemoresistance in breast cancer.
Direct and vicarious conspicuous consumption: Identification with low‐status groups increases the desire for high‐status goods
Authors: Mazzocco Philip J. , Rucker Derek D. , Galinsky Adam D. , Anderson Eric T.
Published: July 2012

The current research examines whether direct and vicarious identification with a low‐status group affects consumers' desire for objects associated with status. Experiment 1 found that individuals who belonged to and identified with a status social category associated with relatively lower status (Blacks) exhibited an enhanced desire for high‐status products compared to Blacks who did not identify with their race or individuals who belonged to a social category associated with higher status (Whites). In Experiments 2 and 3, White participants led to vicariously identify through perspective taking with Blacks (Experiment 2), or a low‐status occupational group (Experiment 3) exhibited an increased desire for high‐status products. Experiment 4 provided meditational evidence for a status based explanation for the relationship between identification with a low‐status group and a desire for high‐status products. The present work makes new inroads into understanding one factor that might lead minorities to engage in greater conspicuous consumption and provides evidence that conspicuous consumption can be elicited vicariously.
Reliability and Consensus of Experienced Wine Judges: Expertise Within and Between?
Authors: Ashton Robert H.
Published: July 2012

This paper considers the levels of reliability and consensus of wine quality judgments found in studies of experienced wine judges. Both reliability, which concerns the similarity of repeat judgments of a particular wine by the same judge, and consensus, which concerns the similarity of judgments of a particular wine across judges, are necessary requirements for expertise in wine judging. Reliability and consensus levels found in wine judging are compared to those documented by a large body of research in six other fields: medicine, clinical psychology, business, auditing, personnel management, and meteorology. In all fields, including wine judging, reliability is greater than consensus. Both reliability and consensus are, on average, substantially lower in wine judging than in other fields, although tremendous variability exists across judges in every field. Overall, little support is found for the idea that experienced wine judges should be regarded as experts. (JEL Classification: C91)