bluuebunny/crossref_metadata_2025_split huggingface dataset:
Theophyllinylpyrimidine Scaffolds Undergo Intramolecular Cyclization Reactions to Form 1,3‐Diazepines and Imidazopurines
Authors: Lebedyeva Iryna O. , Povstyanoy V'yacheslav M. , Ryabitskii Aleksey B. , Panasyuk Oleksandr , Ivahnenko Evgen , Lozova Vera P. , Markevich Igor , Allakhverdova Svitlana , Povstyanoy Mykhaylo V. 
Published: June 2013

AbstractPolyheterocyclic pyrimidinyltheophyllines have been synthesized from pyrimidine and theophylline precursors. Attempts to cyclize these reactive bis‐heterocyclic systems resulted in the formation of the corresponding diazepine moieties. In addition, modification of the reaction conditions led to the formation of imidazo[2,1‐f]purines.
Total Synthesis of the Phenolic Glycolipid Mycoside B and the Glycosylated p‐Hydroxybenzoic Acid Methyl Ester HBAD‐I, Virulence Markers of Mycobacterium tuberculosis
Authors: Barroso Santiago , Geerdink Danny , ter Horst Bjorn , Casas‐Arce Eva , Minnaard Adriaan J. 
Published: June 2013

AbstractThe phenolic glycolipid mycoside B, present in Mycobacterium bovis and hypervirulent strains of Mycobacterium tuberculosis, has been synthesized for the first time. Multiple methyl groups were introduced by the extensive use of catalytic asymmetric 1,4‐addition reactions, asymmetric hydrogenation of a β‐keto ester afforded the basis for the central 1,3‐diol moiety, and introduction of the 2‐O‐methyl‐α‐L‐rhamnoside unit was achieved by stereoselective glycosylation with p‐iodophenol and subsequent Sonogashira coupling, providing a basis for the generation of analogues. In addition, the related monosaccharide HBAD‐I, present in the same species, has been efficiently synthesized for the first time by selective methylation of the hydroxy group at C‐2 of a rhamnoside.
Changes in ecosystem structure, function and hydrological connectivity control water, soil and carbon losses in semi‐arid grass to woody vegetation transitions
Authors: Puttock Alan , Macleod Christopher J.A. , Bol Roland , Sessford Patrick , Dungait Jennifer , Brazier Richard E. 
Published: June 2013

ABSTRACTConnectivity has recently emerged as a key concept for understanding hydrological response to vegetation change in semi‐arid environments, providing an explanatory link between abiotic and biotic, structure and function. Reduced vegetation cover following woody encroachment, generally promotes longer, more connected overland flow pathways, which has the potential to result in an accentuated rainfall‐runoff response and fluxes of both soil erosion and carbon.This paper investigates changing hydrological connectivity as an emergent property of changing ecosystem structure over two contrasting semi‐arid grass to woody vegetation transitions in New Mexico, USA. Vegetation structure is quantified to evaluate if it can be used to explain observed variations in water, sediment and carbon fluxes. Hydrological connectivity is quantified using a flow length metric, combining topographic and vegetation cover data.Results demonstrate that the two woody‐dominated sites have significantly longer mean flowpath lengths (4 · 3 m), than the grass‐dominated sites (2 · 4 m). Mean flowpath lengths illustrate a significant positive relationship with the functional response. The woody‐dominated sites lost more water, soil and carbon than their grassland counterparts. Woody sites erode more, with mean event‐based sediment yields of 1203 g, compared to 295 g from grasslands. In addition, the woody sites lost more organic carbon, with mean event yields of 39 g compared to 5 g from grassland sites.Finally, hydrological connectivity (expressed as mean flowpath length) is discussed as a meaningful measure of the interaction between structure and function and how this manifests under the extreme rainfall that occurs in semi‐arid deserts. In combination with rainfall characteristics, connectivity emerges as a useful tool to explain the impact of vegetation change on water, soil and carbon losses across semi‐arid environments. Copyright © 2013 John Wiley & Sons, Ltd.
Silver nanoparticle toxicity to Daphnia magna is a function of dissolved silver concentration
Authors: Newton Kim M. , Puppala Hema L. , Kitchens Christopher L. , Colvin Vicki L. , Klaine Stephen J. 
Published: June 2013

Abstract

The most persistent question regarding the toxicity of silver nanoparticles (AgNPs) is whether this toxicity is due to the nanoparticles themselves or the silver ions (Ag+) they release. The present study investigates the role of surface coating and the presence of dissolved organic carbon on the toxicity of AgNPs to Daphnia magna and tests the hypothesis that the acute toxicity of AgNPs is a function of dissolved Ag produced by nanoparticle dissolution. Toxicity of silver nitrate (AgNO3) and AgNPs with surface coatings—gum arabic (AgGA), polyethylene glycol (AgPEG), and polyvinylpyrrolidone (AgPVP)—at 48 h was assessed in US Environmental Protection Agency moderately hard reconstituted water alone and augmented with Suwannee River dissolved organic carbon (DOC). As expected, AgNO3 was the most toxic to D. magna and AgPVPs were the least toxic. In general, Suwannee River DOC presence reduced the toxicity of AgNO3, AgGAs, and AgPEG, while the toxicity of AgPVPs was unaffected. The measured dissolved Ag concentrations for all AgNPs and AgNO3 at the 48-h median lethal concentration in moderately hard reconstituted water were similar. The presence of Suwannee River DOC decreased the ratio of measured dissolved Ag to measured total Ag concentration. These results support the hypothesis that toxicity of AgNPs to D. magna is a function of dissolved Ag concentration from these particles. Environ Toxicol Chem 2013;32:2356–2364. © 2013 SETAC
Dysapoptosis of Osteoblasts and Osteocytes Increases Cancellous Bone Formation But Exaggerates Cortical Porosity With Age
Authors: Jilka Robert L , O'Brien Charles A , Roberson Paula K , Bonewald Lynda F , Weinstein Robert S , Manolagas Stavros C 
Published: June 2013

ABSTRACT

Skeletal aging is accompanied by decreased cancellous bone mass and increased formation of pores within cortical bone. The latter accounts for a large portion of the increase in nonvertebral fractures after age 65 years in humans. We selectively deleted Bak and Bax, two genes essential for apoptosis, in two types of terminally differentiated bone cells: the short-lived osteoblasts that elaborate the bone matrix, and the long-lived osteocytes that are immured within the mineralized matrix and choreograph the regeneration of bone. Attenuation of apoptosis in osteoblasts increased their working lifespan and thereby cancellous bone mass in the femur. In long-lived osteocytes, however, it caused dysfunction with advancing age and greatly magnified intracortical femoral porosity associated with increased production of receptor activator of nuclear factor-κB ligand and vascular endothelial growth factor. Increasing bone mass by artificial prolongation of the inherent lifespan of short-lived osteoblasts, while exaggerating the adverse effects of aging on long-lived osteocytes, highlights the seminal role of cell age in bone homeostasis. In addition, our findings suggest that distress signals produced by old and/or dysfunctional osteocytes are the culprits of the increased intracortical porosity in old age. © 2014 American Society for Bone and Mineral Research
Growth From Birth to Adulthood and Bone Phenotype in Early Old Age: A British Birth Cohort Study
Authors: Kuh Diana , Wills Andrew K , Shah Imran , Prentice Ann , Hardy Rebecca , Adams Judith E , Ward Kate , Cooper Cyrus ,   National Survey for Health and Development (NSHD) Scientific and Data Collection Team
Published: June 2013

ABSTRACT

There is growing evidence that early growth influences bone mass in later life but most studies are limited to birth weight and/or early infant growth and dual-energy X-ray absorptiometry (DXA) measurements. In a British birth cohort study with prospective measures of lifetime height and weight, we investigated the growth trajectory in relation to bone in males (M) and females (F) at 60 to 64 years old. Outcomes were DXA measures of hip and spine areal bone density (aBMD) (n = 1658) and pQCT measures of distal and diaphyseal radius cross-sectional area (CSA), strength, and volumetric bone density (vBMD) (n = 1350 of the 1658). Regression models examined percentage change in bone parameters with standardized measures of birth weight, height, and weight. A series of conditional growth models were fitted for height and weight gain (using intervals: birth–2, 2–4, 4–7, 7–15, 15–20, 20–36, and 36–64 years) and height gain (using intervals: 2–4, 4–7, 7–15, and 15–36 years). Birth weight was positively related to bone CSA (M: 1.4%; 95% confidence interval [CI], 0.3%–2.5%; F: 1.3%; 95% CI, 0.3%–2.4% per 1 SD increase in birth weight for diaphyseal CSA) and strength (M: 1.8%; 95% CI, 0.3–3.4; F: 2.0%; 95% CI, 0.5–3.5). No positive associations were found with trabecular, total, or cortical vBMD. One SD change in prepubertal and postpubertal height and weight velocities were associated with between 2% and 5% greater bone CSA and strength. Height gain in later years was negatively associated with trabecular vBMD. Weight gain velocity during the adult years was positively associated with up to 4% greater trabecular and total BMD, and 4% greater aBMD at hip and spine. In a cohort born in the early post-war period, higher birth weight, gaining weight and height faster than others, particularly through the prepubertal and postpubertal periods, was positively related to bone strength, mostly through greater bone CSA, at 60 to 64 years. © 2014 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals, Inc. on behalf of the American Society for Bone and Mineral Research.
Vitamin D Supplementation in Young White and African American Women
Authors: Gallagher J Christopher , Jindal Prachi S , Smith Lynette M 
Published: June 2013

ABSTRACT

There is limited information on the effects of vitamin D on serum 25 hydroxyvitamin D (25OHD) in young people and none on African Americans. The main objective of this trial was to measure the effect of different doses of vitamin D3 on serum 25OHD and serum parathyroid hormone (PTH) in young women with vitamin D insufficiency (serum 25OHD ≤ 20 ng/mL (50 nmol/L). A randomized double-blind placebo-controlled trial of vitamin D3 was conducted in young white and African American women, age 25 to 45 years. A total of 198 healthy white (60%) and African American (40%) women were randomly assigned to placebo, or to 400, 800, 1600, or 2400 IU of vitamin D3 daily. Calcium supplements were added to maintain a total calcium intake of 1000 to 1200 mg daily. The primary outcomes of the study were the final serum 25OHD and PTH levels at 12 months. The absolute increase in serum 25OHD with 400, 800, 1600, and 2400 IU of vitamin D daily was slightly greater in African American women than in white women. On the highest dose of 2400 IU/d, the mixed model predicted that mean 25OHD increased from baseline 12.4 ng/mL (95% confidence interval [CI], 9.2–15.7) to 43.2 ng/mL (95% CI, 38.2–48.1) in African American women and from 15.0 ng/mL (95% CI, 12.3–17.6) to 39.1 ng/mL (95% CI, 36.2–42.0) in white women. There was no significant effect of vitamin D dose on serum PTH in either race but there was a significant inverse relationship between final serum PTH and serum 25OHD. Serum 25OHD exceeded 20 ng/mL in 97.5% of whites on the 400 IU/d dose and between 800 and 1600 IU/d for African Americans. The recommended dietary allowance (RDA) suggested by the Institute of Medicine for young people is 600 IU daily. The increase in serum 25OHD after vitamin D supplementation was similar in young and old, and in white and African American women. © 2014 American Society for Bone and Mineral Research.
Some New Orders of Hadamard and Skew‐Hadamard Matrices
Authors: Đoković Dragomir Ž. , Golubitsky Oleg , Kotsireas Ilias S. 
Published: June 2013

AbstractWe construct Hadamard matrices of ordersand, and skew‐Hadamard matrices of ordersand. As far as we know, such matrices have not been constructed previously. The constructions use the Goethals–Seidel array, suitable supplementary difference sets on a cyclic group and a new efficient matching algorithm based on hashing techniques.
A systematic review of venous thromboembolism prophylaxis strategies in patients with renal insufficiency, obesity, or on antiplatelet agents
Authors: Kebede Sosena , Prakasa Kalpana R. , Shermock Kenneth , Shihab Hasan M. , Brotman Daniel J. , Sharma Ritu , Chelladurai Yohalakshmi , Haut Elliott R. , Singh Sonal , Segal Jodi B. 
Published: June 2013

BACKGROUNDThere is uncertainty about optimal strategies for venous thromboembolism (VTE) prophylaxis among select populations such as patients with renal insufficiency, obesity, or patients taking antiplatelet drugs including aspirin. Their physiologies make prophylaxis particularly challenging.PURPOSEWe performed a comparative effectiveness review of the literature on efficacy and safety of VTE prophylaxis in these populations.DATA SOURCESWe searched MEDLINE, EMBASE, SCOPUS, CINAHL, International Pharmaceutical Abstracts, clinicaltrial.gov, and the Cochrane Library through August 2012. Eligible studies included controlled trials and observational studies.DATA EXTRACTIONTwo reviewers evaluated studies for eligibility, serially abstracted data, and independently evaluated the risk of bias and strength of evidence supporting interventions to prevent VTE in these populations.RESULTSAfter a review of 30,902 citations, we identified 9 controlled studies, 5 of which were trials, and the other 4 were observational studies. Five articles addressed prophylaxis of patients with renal insufficiency, 2 addressed obese patients, and 2 addressed patients on antiplatelet agents. No study tested prophylaxis in underweight patients or those with liver disease. The majority of observational studies had a high risk of bias. The strength of evidence ranged from low to insufficient regarding the comparative effectiveness and safety of VTE prophylaxis among these patients.CONCLUSIONThe current evidence is insufficient regarding optimal VTE prophylaxis for patients with renal insufficiency, obesity, or those who are on antiplatelet drugs including aspirin. High‐quality studies are needed to inform clinicians about the best VTE prophylaxis for these patients. Journal of Hospital Medicine 2013;8:394–401. © 2013 Society of Hospital Medicine
Application of solid‐phase microextraction to the determination of polycyclic aromatic sulfur heterocycles in Bohai Sea crude oils
Authors: Yang Baijuan , Hou Wei , Zhang Kuiying , Wang Xiaoru 
Published: June 2013

A simple and rapid solid‐phase microextraction approach for the isolation of polycyclic aromatic sulfur heterocycles from the aromatic fraction of crude oil is described. 8‐Hydroxyquinoline silica gel impregnated with palladium chloride was used as a sorbent material for extraction. Operational parameters of the extraction solvents have been evaluated and optimized. Benzothiophene, dibenzothiophene, and benzo[b]naphtho[1,2‐d]thiophene and their C1–C4 alkyl derivatives were identified and quantified by GC–MS. Under optimum conditions, the limits of detection for benzothiophene, dibenzothiophene, and benzo[b]naphtho[1,2‐d]thiophene were 0.277, 0.193, and 0.597 μg/g oil, respectively. The recoveries for the polycyclic aromatic sulfur heterocycles ranged from 81.5 to 92.1%, and the linear dynamic range was from 10 to 1000 ng/mL. The developed methodology was tested in the characterization of crude oil samples collected at the DY, SZ, ZH, and HC petroleum oil fields of the Bohai Sea. The results proved that SPE coupled with GC–MS is a promising tool for the quantitative analysis of polycyclic aromatic sulfur heterocycles in crude oils, especially for oil samples with low concentrations of polycyclic aromatic sulfur heterocycles.
An MEKC assay for the therapeutic drug monitoring of cefepime
Authors: Theurillat Regula , Sendi Parham , Thormann Wolfgang 
Published: June 2013

The development of a robust assay based on MEKC for cefepime in human serum and plasma with internal quality assurance is reported. Sample preparation comprises protein precipitation in the presence of SDS at pH 4.5. This is a gentle approach for which decomposition of cefepime during sample handling is negligible. After hydrodynamic sample injection of the supernatant, analysis occurs in a phosphate/borate buffer at pH 9.1 with 75 mM SDS using normal polarity and analyte detection at 257 nm. The MEKC run time interval and throughput are about 5 min and seven samples per hour, respectively. The calibration range for cefepime is 1–60 μg/mL, with 1 μg/mL being the LOQ. The performance of the assay with multilevel internal calibration was assessed with calibration and control samples. The assay is shown to be simple, inexpensive, reproducible, and robust. It was applied to determine cefepime levels in the sera of critically ill patients and to assess the instability of cefepime in patient and control samples. Our data revealed that serum containing cefepime can be stored at ‒20°C for a short time, whereas for long‐term storage, samples have to be kept at ‒70°C.
Assessing Farmers' Knowledge of Weed Species, Crop Type and Soil Management Practices in Relation to Soil Quality Status in Mai‐Negus Catchment, Northern Ethiopia
Authors: Tesfahunegn Gebreyesus Brhane , Tamene Lulseged , Vlek Paul L. G. , Mekonnen Kirubel 
Published: June 2013

AbstractSoil quality (SQ) assessment from farmers' point of view can be used as a primary indicator for planning sustainable agriculture. Despite this fact, limited information is documented with regard to SQ indicators, for example weed species, crop types and management practices from farmers' knowledge perspectives. The aims of this study are to analyse factors that determine farmers' knowledge of SQ, identify SQ indicators of weed species and crop types across different SQ status and assess soil‐and‐crop management practices that maintain SQ in the Mai‐Negus catchment, northern Ethiopia. Fifty‐two farmer household heads were chosen randomly for questionnaire interview. The results showed significant (p ≤ 0·05) differences in the proportion of respondents who used different crop‐and‐soil management practices. The success of overall prediction by the logistic regression model (model χ2 = 0·84, p < 0·01) and level of model correct predictions (86%) indicated that the explanatory variables have sufficiently explained farmers' knowledge of SQ indicators. Provided that other conditions remained constant, the odds ratio of variables such as farmer experience, access to information, farm location, education, field slope and land tenure have significantly increased the likelihood of farmers for being knowledgeable of SQ indicators. This study also demonstrated that most farmers are knowledgeable in identifying weed species, crop types and management practices across various SQ status, which suggests that such SQ indicators should be used to assess SQ status (degradation severity) while locating fields to be intervened using appropriate management strategies. © 2013 The Authors. Land Degradation & Development published by John Wiley & Sons, Ltd.
Monolithic Nanoporous Crystalline Aerogels
Authors: Daniel Christophe , Longo Simona , Ricciardi Rosa , Reverchon Ernesto , Guerra Gaetano 
Published: June 2013

Monolithic aerogels can be easily obtained by drying physical gels formed by linear uncross‐linked polymers. Preparation methods, structure, and properties of these physically cross‐linked polymeric aerogels are reviewed, with particular emphasis to those whose cross‐linking knots are crystallites and, more in particular, crystallites exhibiting nanoporous‐crystalline forms. The latter aerogels present beside disordered amorphous micropores (typical of all aerogels) also all identical nanopores of the crystalline phases. Their outstanding guest transport properties combined with low material cost, robustness, durability, and ease of handling and recycle make these aerogels suitable for applications in chemical separations, purification, and storage as well as in biomedicine. Scientific, technological, and industrial perspectives for monolithic nanoporous‐crystalline polymeric aerogels are also discussed.
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Genetic determinants of swimming motility in the squid light‐organ symbiont Vibrio fischeri
Authors: Brennan Caitlin A. , Mandel Mark J. , Gyllborg Mattias C. , Thomasgard Krista A. , Ruby Edward G. 
Published: June 2013

AbstractBacterial flagellar motility is a complex cellular behavior required for the colonization of the light‐emitting organ of the Hawaiian bobtail squid, Euprymna scolopes, by the beneficial bioluminescent symbiont Vibrio fischeri. We characterized the basis of this behavior by performing (i) a forward genetic screen to identify mutants defective in soft‐agar motility, as well as (ii) a transcriptional analysis to determine the genes that are expressed downstream of the flagellar master regulator FlrA. Mutants with severe defects in soft‐agar motility were identified due to insertions in genes with putative roles in flagellar motility and in genes that were unexpected, including those predicted to encode hypothetical proteins and cell division–related proteins. Analysis of mutants for their ability to enter into a productive symbiosis indicated that flagellar motility mutants are deficient, while chemotaxis mutants are able to colonize a subset of juvenile squid to light‐producing levels. Thirty‐three genes required for normal motility in soft agar were also downregulated in the absence of FlrA, suggesting they belong to the flagellar regulon of V. fischeri. Mutagenesis of putative paralogs of the flagellar motility genes motA, motB, and fliL revealed that motA1, motB1, and both fliL1 and fliL2, but not motA2 and motB2, likely contribute to soft‐agar motility. Using these complementary approaches, we have characterized the genetic basis of flagellar motility in V. fischeri and furthered our understanding of the roles of flagellar motility and chemotaxis in colonization of the juvenile squid, including identifying 11 novel mutants unable to enter into a productive light‐organ symbiosis.