bluuebunny/crossref_metadata_2025_split huggingface dataset:
Improved single-chain transactivators of the Tet-On gene expression system
Authors: Zhou Xue , Symons Jori , Hoppes Rieuwert , Krueger Christel , Berens Christian , Hillen Wolfgang , Berkhout Ben , Das Atze T 
Published: January 2007

Abstract

Background
The Tet-Off (tTA) and Tet-On (rtTA) regulatory systems are widely applied to control gene expression in eukaryotes. Both systems are based on the Tet repressor (TetR) from transposon Tn10, a dimeric DNA-binding protein that binds to specific operator sequences (tetO). To allow the independent regulation of multiple genes, novel Tet systems are being developed that respond to different effectors and bind to different tetO sites. To prevent heterodimerization when multiple Tet systems are expressed in the same cell, single-chain variants of the transactivators have been constructed. Unfortunately, the activity of the single-chain rtTA (sc-rtTA) is reduced when compared with the regular rtTA, which might limit its application.

Results
We recently identified amino acid substitutions in rtTA that greatly improved the transcriptional activity and doxycycline-sensitivity of the protein. To test whether we can similarly improve other TetR-based gene regulation systems, we introduced these mutations into tTA and sc-rtTA. Whereas none of the tested mutations improved tTA activity, they did significantly enhance sc-rtTA activity. We thus generated a novel sc-rtTA variant that is almost as active and dox-sensitive as the regular dimeric rtTA. This variant was also less sensitive to interference by co-expressed TetR-based tTS repressor protein and may therefore be more suitable for applications where multiple TetR-based regulatory systems are used.

Conclusion
We developed an improved sc-rtTA variant that may replace regular rtTA in applications where multiple TetR-based regulatory systems are used.
Silencing of the AV2 gene by antisense RNA protects transgenic plants against a bipartite begomovirus
Authors: Mubin Muhammad , Mansoor Shahid , Hussain Mazhar , Zafar Yusuf 
Published: January 2007

Abstract
Whitefly-transmitted geminiviruses (genus Begomovirus) are phytopathogens that cause heavy losses to crops worldwide. Efforts to engineer resistance against these viruses are focused mainly on silencing of complementary-sense virus genes involved in virus replication. Here we have targeted a virion-sense gene (AV2) to develop resistance against Tomato leaf curl New Delhi virus, a bipartite begomovirus prevalent throughout the Indian subcontinent. We show that tobacco plants transformed with an antisense construct targeting this gene are resistant to the virus. Following challenged with the virus, transgenic plants remained symptomless, although viral DNA could be detected in some plants by PCR. This is the first report of transgenic resistance against a bipartite begomovirus obtained by targeting a virion-sense gene. The relatively conserved nature of the gene suggests that the technology may be useful to develop broad-spectrum resistance which is required because of the fact that plants are often infected with multiple begomoviruses in the field.
Stem cell factor-mediated activation pathways promote murine eosinophil CCL6 production and survival
Authors: Dolgachev Vladislav , Thomas Molly , Berlin Aaron , Lukacs Nicholas W 
Published: January 2007

AbstractEosinophil activation during allergic diseases has a detrimental role in the generation of pathophysiologic responses. Stem cell factor (SCF) has recently shown an inflammatory, gene-activating role on eosinophils and contributes to the generation of pathophysiologic changes in the airways during allergic responses. The data in the present study outline the signal transduction events that are induced by SCF in eosinophils and further demonstrate that MEK-mediated signaling pathways are crucial for SCF-induced CCL6 chemokine activation and eosinophil survival. SCF-mediated eosinophil activation was demonstrated to include PI-3K activation as well as MEK/MAPK phosphorylation pathways. Subsequent analysis of CCL6 gene activation and production induced by SCF in the presence or absence of rather specific inhibitors for certain pathways demonstrated that the MEK/MAPK pathway but not the PI-3K pathway was crucial for the SCF-induced CCL6 gene activation. These same signaling pathways were shown to initiate antiapoptotic events and promote eosinophil survival, including up-regulation of BCL2 and BCL3. Altogether, SCF appears to be a potent eosinophil activation and survival factor.
Cell-Free mRNA Concentrations of Plasminogen Activator Inhibitor-1 and Tissue-Type Plasminogen Activator Are Increased in the Plasma of Pregnant Women with Preeclampsia
Authors: Purwosunu Yuditiya , Sekizawa Akihiko , Koide Keiko , Farina Antonio , Wibowo Noroyono , Wiknjosastro Gulardi Hanifa , Okazaki Shiho , Chiba Hiroshi , Okai Takashi 
Published: January 2007

Abstract
Background: Detection of placental mRNA in maternal plasma has been reported in high-risk pregnancies. We attempted to investigate the concentrations of plasminogen activator inhibitor-1 (PAI-1) and tissue-type plasminogen activator (tPA) mRNA in maternal plasma in preeclampsia.
Methods: Peripheral blood samples were obtained from healthy pregnant women before and after delivery and also from women with or without preeclampsia. Plasma was isolated from these samples, and RNA was extracted. Plasma PAI-1 and tPA mRNA concentrations were then measured by use of reverse transcription PCR assays. The concentrations were converted into multiples of the median (MoM) of the controls adjusted for gestational age. Data were stratified and analyzed according to the clinical severity of preeclampsia and quantitative distribution of blood pressure and proteinuria.
Results: The median (minimum–maximum) PAI-1 mRNA MoM values for women with preeclampsia and controls were 2.48 (0.82–8.53) and 1.00 (0.41–2.33), respectively, whereas the median (minimum–maximum) tPA mRNA MoM values were 3.33 (1.01–10.58) and 1.00 (0.95–1.20), respectively. The concentrations of both PAI-1 and tPA mRNA were significantly increased in cases of preeclampsia, compared with controls (P &lt;0.0001). The MoM values of both mRNA species were directly correlated with the severity of preeclampsia and were greatest among a subgroup of hemolysis, increased liver enzymes, and low platelets pregnancies.
Conclusion: Maternal plasma PAI-1 and tPA mRNAs are significantly increased in patients with preeclampsia and are positively correlated with the severity of preeclampsia.
Respiratory impairment in Brazilian foundry workers exposed to sand
Authors: Mendonça E.M.C. , Silva R.C.C. , Bussacos M.A. , Algranti E. 
Published: January 2007

AbstractObjectiveFoundries date back to the 16th century in Brazil and still constitute a strong economic activity today. Workers are at risk of respiratory diseases due to various exposures such as polycyclic aromatic hydrocarbons, pyrolysis degradation products, mineral dust, organic dust, resin, and isocyanates. We evaluate respiratory morbidity among workers in foundries using sand.MethodsSix foundries with sand molding operations were selected. Length of exposure in years was utilized as a surrogate for exposure. The medical evaluation consisted of a respiratory symptoms questionnaire, occupational history, spirometry, and chest X‐rays. Additionally, workers exposed to resins and a control group underwent bronchial provocation tests.ResultsA sample of 598 male workers with a mean age of 36.5 years (SD = 10.0) was analyzed. The mean length of exposure was 10.1 years (SD = 7.4). The overall prevalence of pneumoconiosis was 4.5%. Chronic bronchitis (CB) and X‐ray profusion were significantly related to the quartiles of length of exposure (trend tests: P = 0.0055 and P < 0.001, respectively). There was a significant risk of having an abnormal FVC and FEV1 with the presence of pneumoconiosis (OR = 4.63 CI 1.40‐13‐23, OR 3.34 CI 1.03–9.26, respectively). Workers exposed to resins compared with controls showed no differences in relation to spirometry, respiratory symptoms and bronchial reactivity.ConclusionsThere were significant associations between length of exposure CB and prevalence of profusion 1/0 or above. There was also a significant association for pneumoconiosis versus and abnormal FVC and FEV1. Foundry workers currently exposed to resins did not show an excess of respiratory symptoms, abnormal spirometry or increased bronchial reactivity. Am. J. Ind. Med. 50:83–91, 2007. © 2006 Wiley‐Liss, Inc.
A multi‐faceted approach to risk assessment of laboratory animal allergens at two facilities
Authors: Korpi A. , Lappalainen S. , Kaliste E. , Kalliokoski P. , Reijula K. , Pasanen A.‐L. 
Published: January 2007

AbstractBackgroundRisk assessment of exposure to allergens is difficult because the relationship between exposure, sensitization, and symptoms has not been fully established. Laboratory animal allergens (LAA) are an important occupational health risk factor; 10–32% of workers exposed to these allergens develop allergic diseases. This article introduces a versatile approach to assessing the risks posed by LAA at two laboratory animal facilities.MethodsThe risk assessment approach that was used at the laboratory animal facilities included questionnaires for management and employees, a hazard identification visit and measurements in the workplaces, as well as the creation of a list of generally recommended procedures to reduce allergen exposure.ResultsThe prevalence of work‐related allergic symptoms was 17%. Suggested countermeasures at the sites included changes in ventilation and work practices, reduction of unnecessary exposure, recommendations for more comprehensive use of personal protective equipment, and wider communication about LAA risks.ConclusionsThe approach managed to identify critical points and potential means for controlling LAA exposure. Am. J. Ind. Med. 50:127–135, 2007. © 2006 Wiley‐Liss, Inc.
Chemical depolymerization of dextran sulfate sodium—the application of size‐exclusion or ion‐pair liquid chromatography
Authors: Araki Yoshio , Sugihara Hiroyuki , Hattori Takanori 
Published: January 2007

AbstractWe reported previously a method for the separation and quantification of sulfated polysaccharides, dextran sulfate sodium (DSS), using fluorometric labeling and size‐exclusion chromatography (SEC). In the present study, we evaluated chemical depolymerization of DSS. In fluorometric analyses using SEC, pyridylamino‐DSS (PA‐DSS) was depolymerized under acidic conditions, but not under alkaline conditions. In addition, we used ion‐pair liquid chromatography (IPLC) and UV analyses for the separation and quantification of sulfate. Sulfate was considerably depleted from DSS under alkaline conditions, but little depleted under acidic conditions. Spectrophotometric studies using toluidine blue revealed that molecular mass is an important factor and a minimum molecular mass of 2500 is needed to induce metachromasia. Fluorometric analyses using SEC and UV analyses using IPLC allow for the detection of DSS, reactants and sulfate. Copyright © 2007 John Wiley & Sons, Ltd.
Determination of plasma free 3‐nitrotyrosine and tyrosine by reversed‐phase liquid chromatography with 4‐fluoro‐7‐nitrobenzofurazan derivatization
Authors: Zhang Wei‐Zheng , Lang Charles , Kaye David M. 
Published: January 2007

AbstractOxidative stress plays an important role in pathogenesis of many diseases. Measurement of 3‐nitrotyrosine (NO2Tyr), as a potential biomarker for nitric oxide‐mediated damage, has recently been the focus of particular attention. We have developed an HPLC method with NBD‐F pre‐column derivatization followed by C18 cartridge cleaning. Using this method we achieved limits of detection of 0.5 and 1.1 nm for NO2Tyr and tyrosine (Tyr), respectively, close to that achieved by LS‐MS/MS. NO2Tyr and tyrosine concentrations were linear over the calibration ranges 0.5–100 nm and 1–320 µm, respectively, with correlation coefficients greater than 0.95. To evaluate the utility of this assay in plasma we analysed samples obtained from smokers and non‐smoking subjects. Consistent with the presence of elevated oxidative stress, the plasma NO2Tyr concentration and NO2Tyr:Tyr ratio of smokers were 17.42 ± 11.6 nm and 0.263 ± 0.192 nm/µm with 3.8 and 3.9 times higher (both p < 0.05), respectively, than that of non‐smoker controls (4.54 ± 2.75 nm and 0.067 ± 0.050 nm/µm, respectively). In conclusion, we have developed a novel HPLC assay for NO2Tyr without MS detection that is applicable to clinical studies addressing the pathophysiology and importance of oxidative stress. Copyright © 2007 John Wiley & Sons, Ltd.
Development and validation of a reversed‐phase HPLC method for determination of nitrendipine in rat plasma: application to pharmacokinetic studies
Authors: Venishetty Vinay Kumar , Durairaj Chandrasekar , Sistla Ramakrishna , Yamsani Madhusudhan Rao , Diwan Prakash V. 
Published: January 2007

AbstractA simple and sensitive method for the determination of nitrendipine in rat plasma was developed using high‐performance liquid chromatography (HPLC). The procedure involves extraction of nitrendipine in dichloromethane/sodium hydroxide, followed by reversed phase HPLC using a Waters, Spherisorb ODS2 (250 × 4.6 mm, 5 µm) column and UV detection at 238 nm. The retention times of nitrendipine and internal standard (felodipine) were 5.0 min and 7.5 min, respectively. The calibration curves were linear over the range of 5 ng/mL (lower limit of quantification, LOQ) to 200 ng/mL for nitrendipine. The intra‐ and inter‐day coefficients of variation for all criteria of validation were less than 15% over the linearity range. The sensitivity and precision of the method were within the accepted limits (< 15%) throughout the validation period. The present method was also successfully applied for the study of plasma pharmacokinetics of nitrendipine loaded solid lipid nanoparticles (SLN) in rats. Copyright © 2007 John Wiley & Sons, Ltd.
Simultaneous determination of ZLR‐8 and its active metabolite diclofenac in dog plasma by high‐performance liquid chromatography
Authors: Jiao Haoyan , Xu Fengguo , Zhang Zunjian , Tian Yuan , Jiang Zhenzhou , Zhang Luyong 
Published: January 2007

AbstractZLR‐8 is a nitric oxide releasing derivative of diclofenac for the treatment of inflammation. In this paper, a sensitive and reliable high‐performance liquid chromatography method for simultaneous determination of ZLR‐8 and its active metabolite diclofenac in the plasma of beagle dogs has been developed and validated. After the addition of ketoprofen as the internal standard (IS), plasma samples were extracted with n‐hexane–isopropanol (95:5, v/v) mixture solution and separated by HPLC on a reversed‐phase C18 column with a mobile phase of gradient procedure. Analytes were determined by the UV detector which was set at 280 nm. The method was proved to be sensitive and specific by testing six different plasma batches. Calibration curves of ZLR‐8 and diclofenac were linear over the range 0.05–4.0 µg/mL. The within‐ and between‐batch precisions (RSD%) were lower than 10% and accuracy ranged from 85 to 115%. The lower limit of quantification was identifiable and reproducible at 0.05 µg/mL. The proposed method has been readily implemented in preclinical pharmacokinetics studies of ZLR‐8 and its active metabolite diclofeance. Representative plasma concentration vs time profiles resulting from administration of ZLR‐8 to beagle dogs are presented in this communication. Copyright © 2007 John Wiley & Sons, Ltd.
An automated method for peak detection and matching in large gas chromatography‐mass spectrometry data sets
Authors: Dixon Sarah J. , Brereton Richard G. , Soini Helena A. , Novotny Milos V. , Penn Dustin J. 
Published: January 2007

AbstractA new approach for peak detection and matching has been developed and applied to two data sets. The first consisted of the Gas Chromatography‐Mass Spectrometry (GC‐MS) samples of 965 human sweat samples obtained from a population of 197 individuals. The second data set contained 500 synthetic chromatograms, and was generated to validate the peak detection and matching methods. The size of both of the data sets (around 500 000 detectable peaks over all chromatograms in data set 1, and around 100 000 in data set 2) would make it unfeasible to check manually whether peaks are matched. In the method described, the first procedure involves pre‐processing the data before carrying out the second procedure of peak detection. The final procedure of peak matching consists of three stages: (a) finding potential target peaks in the full data set over all chromatograms; (b) matching peaks in the chromatograms to these targets to form clusters of spectra associated with each target; (c) merging targets where appropriate. Peak detection and matching were applied to both data sets, and the importance of stage (c) of peak matching described. In addition to the analysis of the synthetic chromatograms, the method was also validated by shuffling the original order of the sweat chromatograms and performing the methods independently on the newly shuffled data. Copyright © 2007 John Wiley & Sons, Ltd.
Proton Walk in the Aqueous Platinum Complex [TpPtMeCO] via a Sticky σ‐Methane Ligand
Authors: Lo H. Christine , Iron Mark A. , Martin Jan M. L. , Keinan Ehud 
Published: January 2007

AbstractBoth experimental and theoretical evidence suggest that the proton exchange between water and the methyl group in [TpPt(CO)CH3] (1, Tp=hydridotripyrazolylborate) involves the formation and deprotonation of a “sticky” σ‐methane ligand. The efficiency of this nontrivial process has been attributed to the spatial orientation of functional groups that operate in concert to activate a water molecule and then achieve a multistep proton walk from water to an uncoordinated pyrazolyl nitrogen atom, to the methyl ligand, and then back to the nitrogen atom and water. The overall proton‐exchange process has been proposed to involve an initial attack of water at the CO ligand in 1 with concerted deprotonation by the uncoordinated pyrazolyl nitrogen atom. The pyrazolium proton is then transferred to the PtCH3 bond, leading to a σ‐methane intermediate. Subsequent rotation and deprotonation of the σ‐methane ligand, followed by reformation of 1 and water, result in scrambling of the methyl protons with the hydrogen atoms of water. An alternative two‐step process that involves oxidative addition and reductive elimination has also been considered. The two competing mechanistic routes from 1 into [D3]‐1, as well as the conversion of 1 into [TpPt(CH3)H2] (2), have been examined by density functional theory (DFT) using a variety of exchange‐correlation methods, primarily PW6B95, which was recently shown to be highly accurate for evaluating reactions of late‐transition‐metal complexes. The key role played by the free pyrazolyl nitrogen atom, acting as a proton carrier that abstracts a proton from water and transfers the proton to the PtCH3 bond, is reminiscent of the dual functionality of histidine in the catalytic triad of natural serine proteases.
Changes in cholesterol levels in the plasma membrane modulate cell signaling and regulate cell adhesion and migration on fibronectin
Authors: Ramprasad O. G. , Srinivas G. , Rao K. Sridhar , Joshi Powrnima , Thiery Jean Paul , Dufour Sylvie , Pande Gopal 
Published: January 2007

AbstractThe number and distribution of lipid molecules, including cholesterol in particular, in the plasma membrane, may play a key role in regulating several physiological processes in cells. We investigated the role of membrane cholesterol in regulating cell shape, adhesion and motility. The acute depletion of cholesterol from the plasma membrane of cells that were well spread and motile on fibronectin caused the rounding of these cells and decreased their adhesion to and motility on fibronectin. These modifications were less pronounced in cells plated on laminin, vitronectin or plastic, indicating that cholesterol‐mediated changes in adhesion and motility are more specific for adhesion mediated by fibronectin‐specific integrins, such as α5β1. These changes were accompanied by remodeling of the actin cytoskeleton, the spatial reorganization of paxillin in the membrane, and changes to the dynamics of α5 integrin and paxillin‐rich focal adhesions. Levels of tyrosine phosphorylation at position 576/577 of FAK and Erk1/Erk2 MAP‐kinase activity levels were both lower in cholesterol‐depleted than in control cells. These levels normalized only on fibronectin when cholesterol was reincorporated into the cell membrane. Thus, membrane cholesterol content has a specific effect on certain signaling pathways specifically involved in regulating cell motility on fibronectin and organization of the actin cytoskeleton. Cell Motil. Cytoskeleton © 2007 Wiley‐Liss, Inc.
Rates of myocardial infarction and coronary artery disease and risk factors in patients treated with radiation therapy for early‐stage breast cancer
Authors: Jagsi Reshma , Griffith Kent A. , Koelling Todd , Roberts Rachel , Pierce Lori J. 
Published: January 2007

AbstractBACKGROUND.Radiation therapy (RT), a critical component of breast‐conserving therapy for breast cancer, has been associated with coronary artery disease (CAD) in numerous older studies, but the risk may be lower with modern techniques.METHODS.Observed rates of cardiac events in 828 patients treated with breast‐conserving surgery and RT at the University of Michigan were compared with expected rates. Relations between potential risk factors and actuarial rates of first CAD event were analyzed.RESULTS.Observed risks of cardiac events were lower than expected. The standardized incidence ratio (SIR) of myocardial infarction (MI) was 0.44 (95% confidence interval [CI]: 0.21–0.70). The SIR of MI or CAD requiring intervention was 0.50 (95% CI: 0.27–0.68). With a median follow‐up of 6.8 years, 12 (1.4%) patients had at least 1 MI on follow‐up and 20 (2.4%) had at least 1 MI or CAD requiring intervention. Median age at first cardiac event was 75.9 years (range, 43.1–91.5). Median interval from RT to occurrence of the first cardiac event was 3.7 years (range, 13 days to 15.4 years). The 10‐year cumulative incidence of MI was 1.2% and cumulative incidence of MI or CAD requiring intervention was 2.7%. On multivariate analysis, age, diabetes mellitus, active smoking, and laterality of RT were significant predictors of MI. Age and active smoking were significant predictors of MI or CAD requiring intervention.CONCLUSIONS.Patients in this series had lower risk of ischemic cardiac events than expected. Although small in absolute magnitude, patients radiated to the left side did have a statistically significant increased risk of MI. These findings support further investigation of techniques to minimize the long‐term cardiac risks faced by breast cancer patients. Cancer 2007 © 2007 American Cancer Society.