bluuebunny/crossref_metadata_2025_split huggingface dataset:
Identification of two residues essential for the stringent substrate specificity and active site stability of the prokaryotic l‐arginine:glycine amidinotransferase CyrA
Authors: Muenchhoff Julia , Siddiqui Khawar S. , Neilan Brett A. 
Published: January 2012

A novel prokaryotic l‐arginine:glycine amidinotransferase (CyrA; EC2.1.4.1) is involved in the biosynthesis of the polyketide‐derived cytotoxin cylindrospermopsin in the cyanobacterium Cylindrospermopsis raciborskii AWT250, and was previously characterized with regard to kinetic mechanism and substrate specificity [Muenchhoff J et al. (2010) FEBS J277, 3844–3860]. In order to elucidate the structure–function–stability relationship of this enzyme, two residues in its active site were replaced with the residues that occur in the human l‐arginine:glycine amidinotransferase (h‐AGAT) at the corresponding positions (F245N and S247M), and a double variant carrying both substitutions was also created. In h‐AGAT, both of these residues are critical for the function of this enzyme with regard to substrate binding, ligand‐induced structural changes, and stability of the active site. In this study, we demonstrated that both single residue replacements resulted in a dramatic broadening of substrate specificity, but did not affect the kinetic mechanism. Experiments with substrate analogues indicate that donor substrates require a carboxylate group for binding. Evidence from initial velocity studies suggests that CyrA undergoes ligand‐induced structural changes that involve Phe245. Stability parameters (Topt and Tmax) of the CyrA variants differed from those of wild‐type CyrA. Structural flexibilities of the wild type and all three variants were comparable on the basis of dynamic fluorescence quenching, indicating that changes in Topt are most likely attributable to localized effects within the active site. Overall, the results indicated that these two residues are essential for both stringent substrate specificity and the active site stability and flexibility of this unique cyanobacterial enzyme.
Different Potassium Channels are Involved in Relaxation of Rat Renal Artery Induced by P1075
Authors: Novakovic Aleksandra , Pavlovic Marija , Milojevic Predrag , Stojanovic Ivan , Nenezic Dragoslav , Jovic Miomir , Ugresic Nenad , Kanjuh Vladimir , Yang Qin , He Guo‐Wei 
Published: January 2012

AbstractThe ATP‐sensitive K+ channels opener (KATPCO), P1075 [N‐cyano‐N′‐(1,1‐dimethylpropyl)‐N″‐3‐pyridylguanidine], has been shown to cause relaxation of various isolated animal and human blood vessels by opening of vascular smooth muscle ATP‐sensitive K+ (KATP) channels. In addition to the well‐known effect on the opening of KATP channels, it has been reported that vasorelaxation induced by some of the KATPCOs includes some other K+ channel subtypes. Given that there is still no information on other types of K+ channels possibly involved in the mechanism of relaxation induced by P1075, this study was designed to examine the effects of P1075 on the rat renal artery with endothelium and with denuded endothelium and to define the contribution of different K+ channel subtypes in the P1075 action on this blood vessel. Our results show that P1075 induced a concentration‐dependent relaxation of rat renal artery rings pre‐contracted by phenylephrine. Glibenclamide, a selective KATP channels inhibitor, partly antagonized the relaxation of rat renal artery induced by P1075. Tetraethylammonium (TEA), a non‐selective inhibitor of Ca2+‐activated K+ channels, as well as iberiotoxin, a most selective blocker of large‐conductance Ca2+‐activated K+ (BKCa) channels, did not abolish the effect of P1075 on rat renal artery. In contrast, a non‐selective blocker of voltage‐gated K+ (KV) channels, 4‐aminopyridine (4‐AP), as well as margatoxin, a potent inhibitor of KV1.3 channels, caused partial inhibition of the P1075‐induced relaxation of rat renal artery. In addition, in this study, P1075 relaxed contractions induced by 20 mM K+, but had no effect on contractions induced by 80 mM K+. Our results showed that P1075 induced strong endothelium‐independent relaxation of rat renal artery. It seems that KATP, 4‐AP‐ and margatoxin‐sensitive K+ channels located in vascular smooth muscle mediated the relaxation of rat renal artery induced by P1075.
Plant and Yeast NHX Antiporters: Roles in Membrane TraffickingF
Authors: Qiu Quan‐Sheng 
Published: January 2012

AbstractThe plant NHX gene family encodes Na+/H+ antiporters which are crucial for salt tolerance, potassium homeostasis and cellular pH regulation. Understanding the role of NHX antiporters in membrane trafficking is becoming an increasingly interesting subject of study. Membrane trafficking is a central cellular process during which proteins, lipids and polysaccharides are continuously exchanged among membrane compartments. Yeast ScNhx1p, a prevacuole/ vacuolar Na+/H+ antiporter, plays an important role in regulating pH to control trafficking out of the endosome. Evidence begins to accumulate that plant NHX antiporters might function in regulating membrane trafficking in plants.
image

[ Quan‐Sheng Qiu (Corresponding author)]
Expression of Mitochondrial Gene Fragments within the Tapetum Induce Male Sterility by Limiting the Biogenesis of the Respiratory Machinery in Transgenic TobaccoF
Authors: Shaya Felix , Gaiduk Svetlana , Keren Ido , Shevtsov Sofia , Zemah Hanita , Belausov Eduard , Evenor Dalia , Reuveni Moshe , Ostersetzer‐Biran Oren 
Published: January 2012

AbstractPlant mitochondrial genomes (mtDNAs) are large and undergo frequent recombination events. A common phenotype that emerges as a consequence of altered mtDNA structure is cytoplasmic‐male sterility (CMS). The molecular basis for CMS remains unclear, but it seems logical that altered respiration activities would result in reduced pollen production. Analysis of tobacco (Nicotiana tabacum) mtDNAs indicated that CMS‐associated loci often contain fragments of known organellar genes. These may assemble with organellar complexes and thereby interfere with normal respiratory functions. Here, we analyzed whether the expression of truncated fragments of mitochondrial genes (i.e. atp4, cox1 and rps3) may induce male sterility by limiting the biogenesis of the respiratory machinery. cDNA fragments corresponding to atp4f, cox1f and rps3f were cloned in‐frame to a mitochondrial localization signal and a C‐termini HA‐tag under a tapetum‐specific promoter and introduced to tobacco plants by Agrobacterium‐mediated transformation. The constructs were then analyzed for their effect on mitochondrial activity and pollen fertility. Atp4f, Cox1f and Rps3f plants demonstrated male sterility phenotypes, which were tightly correlated with the expression of the recombinant fragments in the floral meristem. Fractionation of native organellar extracts showed that the recombinant ATP4f‐HA, COX1f‐HA and RPS3f‐HA proteins are found in large membrane‐associated particles. Analysis of the respiratory activities and protein profiles indicated that organellar complex I was altered in Atp4f, Cox1f and Rps3f plants.
Low Molecular Weight Iron Dextran Increases Fibroblast Growth Factor‐23 Concentration, Together With Parathyroid Hormone Decrease in Hemodialyzed Patients
Authors: Hryszko Tomasz , Rydzewska‐Rosolowska Alicja , Brzosko Szymon , Koc‐Zorawska Ewa , Mysliwiec Michal 
Published: January 2012

AbstractFibroblast growth factor (FGF)‐23 inhibits PTH production. Elevated FGF‐23 and parathyroid hormone (PTH) levels are characteristic of hemodialyzed patients. Iron polymaltose was shown to increase FGF‐23 concentration. The effect of intravenous low molecular weight iron dextran (LMID) on these hormones and bone metabolism has not been studied in hemodialysis (HD). Twelve HD patients were prospectively followed up for 3 weeks after a single infusion of LMID. Calcium, phosphate, FGF‐23, PTH, degradation products of C‐terminal telopeptides of type I collagen (CTX) and procollagen I N‐terminal propeptide (PINP) were measured prior to, and at week 1 and week 3 after the LMID administration. FGF‐23 increased significantly from 453.4 (68.6–3971.5) pg/mL at baseline to 971.8 (779.5–3361.4) pg/mL (P = 0.001) at week 1 and started to decrease toward the initial value at week 3. The changes were accompanied by a significant decline in PTH from 367.6 (21.4–1487.4) pg/mL at baseline to 315.7 (16.4–1339.8) pg/mL (P = 0.018) at week 1 and subsequently began to increase toward the initial values. Phosphate, calcium, CTX and PINP did not change over the study course. LMID causes an increase in FGF‐23 concentration together with a decrease in PTH. Our study highlights a pathophysiological element, which may connect suppression of parathyroid glands with intravenous iron supplementation.
Effect of Heparin on Conformation of the β2‐Microglobulin Molecule
Authors: Uji Yoshinori , Motomiya Yoshihiro , Ando Yukio 
Published: January 2012

AbstractHeparin, one of the essential molecules called glycosaminoglycans (GAGs), is the anticoagulant that is commonly used in regular hemodialysis, during which dialysis‐related amyloidosis (DRA) may develop. The pathogenic protein, i.e. precursor protein, in DRA is β2‐microglobulin (β2m). Recent studies defined amyloidosis as a protein misfolding disease of precursor proteins including β2m. Because the analytic technique capillary electrophoresis can identify molecular variants of the folded β2m, i.e. conformational variants, we utilized it to investigate the effect of heparin on β2m conformation and thus determined whether heparin can promote DRA development by inducing a conformational change in the amyloidogenic β2m molecule. Heparin had a slight but significant effect on intermediate β2m conformation but no effect on native β2m conformation and on conversion of native to intermediate β2m. Our findings thus suggest a possible association of β2m with GAGs containing a sulfate moiety, including heparin, in HD patients.
Establishment of a Microplate‐Formatted Cell‐Based Immunoassay for Rapid Analysis of Nucleotide Excision Repair Ability in Human Primary Cells
Authors: Nishinaga Mari , Kurata Ryuichiro , Onishi Kazuyoshi , Kuriyama Kenichi , Wakasugi Mitsuo , Matsunaga Tsukasa 
Published: January 2012

AbstractDNA photolesions induced by UV, cyclobutane pyrimidine dimer (CPD) and (6‐4) photoproduct (6‐4PP), are repaired by nucleotide excision repair (NER) in human cells. Various immunoassays using monoclonal antibodies specific for the photolesions have been developed and widely used for the analysis of cellular NER activity. In this study, we have newly developed a microplate‐formatted cell‐based immunoassay, based on indirect immunofluorescence staining with lesion‐specific antibodies combined with an infrared imaging system. Using this assay, we show the repair kinetics of CPD and 6‐4PP in various fibroblasts from newborn and adult donors with no age‐related difference. Furthermore, epidermal keratinocytes and melanocytes exhibit comparable NER activity, and calcium ion‐induced differentiation of keratinocytes has no significant impacts on their NER activity. We also evaluated the effects of a proteasome inhibitor, MG132, and a histone deacetylase inhibitor, sodium butyrate, on NER efficiency using this assay. All these results suggest that the new assay is highly useful for the rapid and quantitative analysis of NER activity in various primary cells with limited growth activity and is applicable to a screening system for drugs affecting NER efficiency.
Sources and Sinks of Phosphorus for a Perturbed Stream and the Effects of Mineral Deposits1
Authors: Effler Steven W. , Prestigiacomo Anthony R. , Matthews David A. , Peng Feng 
Published: January 2012

Effler, Steven W., Anthony R. Prestigiacomo, David A. Matthews, and Feng Peng, 2012. Sources and Sinks of Phosphorus for a Perturbed Stream and the Effects of Mineral Deposits. Journal of the American Water Resources Association (JAWRA) 48(2): 321‐335. DOI: 10.1111/j.1752‐1688.2011.00617.xAbstract:  Patterns of concentrations and loading rates of multiple forms of phosphorus (P) are resolved and analyzed along Ninemile Creek, New York, a stream perturbed by a domestic waste discharge and residual effects of a closed industry. This analysis is based on biweekly monitoring of total, dissolved, and soluble reactive P (SRP) for 19 months at four sites that bracket each of these effects, and 15 years of biweekly measurements at the two sites that bound industrial deposits. The minerogenic particle populations of the stream and the surficial sediments along the reach with extensive CaCO3 and clay mineral deposits are characterized with an individual particle analysis technique. Mass balance analyses depict: (1) increasing nonpoint inputs of particulate and dissolved organic P along the stream length; (2) input of P from a domestic waste facility, almost entirely in the form of SRP; and (3) a compensating downstream loss of SRP over the reach with the extensive industrial deposits of CaCO3. The downstream sink process for SRP is attributed to sorption processes with minerogenic deposits. The domestic waste‐based source and the compensating industrial waste‐based sink are noteworthy fluxes relative to other prevailing loads received by downstream Onondaga Lake, for which a major rehabilitation program targeting cultural eutrophication is underway. The P source/sink conditions of this stream are considered in the context of this rehabilitation program.
A Sampler for Measuring Deposited Fine Sediments in Streams1
Authors: Turner Andy W. , Hillis Jeff J. , Rabeni Charles F. 
Published: January 2012

Turner, Andy W., Jeff J. Hillis, and Charles F. Rabeni, 2012. A Sampler for Measuring Deposited Fine Sediments in Streams. Journal of the American Water Resources Association (JAWRA) 48(2): 366‐378. DOI: 10.1111/j.1752‐1688.2011.00618.xAbstract:  Improvements and standardization of methodologies to quickly and accurately quantify deposited sediment in streams will allow advances in our understanding of biological effects of sedimentation. Most methods used to evaluate streambed conditions as part of biological monitoring or assessment programs are selected for ease of use, but can be subjective, inappropriate, and often of unknown accuracy. We developed a portable, light‐weight device to quantify deposited unconsolidated sediment (particles <2 mm) in wadeable streams. This deposited sediment sampler is a hand‐held unit that circumscribes an area of the streambed and through suction creates a force that suspends unconsolidated materials into a collector. Laboratory evaluations determined the efficiency (percent of available deposited sediment recovered) of the sampler to collect different sizes and concentrations of deposited sediment under differing streambed conditions, which allowed appropriate correction factors to be applied to each of four categories of streambed particle size. Field trials comparing our sampler to other methods commonly used by many state and federal agencies showed high comparability. The sampler can be constructed in just a few hours from inexpensive, easily obtained materials.
Evaluation of a Recombinant Multiepitope Peptide for Serodiagnosis of Toxoplasma gondii Infection
Authors: Dai Jianfang , Jiang Min , Wang Yanyun , Qu Lili , Gong Rujun , Si Jin 
Published: January 2012

ABSTRACTDetection ofToxoplasma gondiiinfection with sensitive and specific methods is a key step in the prevention and treatment of toxoplasmosis. Among the available diagnostic tests, serology is commonly used. Although serological tests give satisfactory results, the production of reliable reagents remains laborious and expensive. There is therefore a real need to acquire specific and effective recombinant antigens for the serodiagnosis ofT. gondiiinfection. In this study, a multiepitope peptide was designed and successfully expressed inEscherichia coli, and then IgG and IgM enzyme-linked immunosorbent assays (ELISAs) were developed and evaluated. Our results showed that the new multiepitope antigen is one of the most promising recombinant antigens which could be used in routine screening of human toxoplasmosis.
Multisite Reproducibility of the Broth Microdilution Method for Susceptibility Testing of Nocardia Species
Authors: Conville Patricia S. , Brown-Elliott Barbara A. , Wallace Richard J. , Witebsky Frank G. , Koziol Deloris , Hall Geraldine S. , Killian Scott B. , Knapp Cindy C. , Warshauer David , Van Tam , Wengenack Nancy L. , Deml Sharon , Woods Gail L. 
Published: January 2012

ABSTRACT

Antimicrobial susceptibility testing (AST) of clinical isolates of
Nocardia
is recommended to detect resistance to commonly used antimicrobial agents; such testing is complicated by difficulties in inoculum preparation and test interpretation. In this study, six laboratories performed repetitive broth microdilution testing on single strains of
Nocardia brasiliensis
,
Nocardia cyriacigeorgica
,
Nocardia farcinica
,
Nocardia nova
, and
Nocardia wallacei
. For each isolate, a total of 30 microdilution panels from three different lots were tested at most sites. The goal of the study was to determine the inter- and intralaboratory reproducibility of susceptibility testing of this group of isolates. Acceptable agreement (>90% agreement at ±1 dilution of the MIC mode) was found for amikacin, ciprofloxacin, clarithromycin, and moxifloxacin. After eliminating MIC values from single laboratories whose results showed the greatest deviation from those of the remaining laboratories, acceptable agreement was also found for amoxicillin-clavulanic acid, linezolid, minocycline, and tobramycin. Results showed unsatisfactory reproducibility of broth microdilution testing of ceftriaxone with
N. cyriacigeorgica
and
N. wallacei
, tigecycline with
N. brasiliensis
and
N. cyriacigeorgica
, and sulfonamides with
N. farcinica
and
N. wallacei. N. nova
ATCC BAA-2227 is proposed as a quality control organism for AST of
Nocardia
sp., and the use of a disk diffusion test for sulfisoxazole is proposed as a check of the adequacy of the inoculum and to confirm sulfonamide MIC results.
Risk factors for ischaemic heart disease mortality among men with different occupational physical demands. A 30-year prospective cohort study
Authors: Holtermann Andreas , Mortensen Ole Steen , Søgaard Karen , Gyntelberg Finn , Suadicani Poul 
Published: January 2012

ObjectivesMen with high physical work demands have elevated cardiovascular strain, which may lead to enhanced atherosclerosis. Theoretically, the impact of risk factors for ischaemic heart disease (IHD) may thus depend on physical work demands. The authors investigated this hypothesis.DesignProspective 30-year follow-up.SettingThe Copenhagen Male Study.Participants5249 gainfully employed men aged 40–59 years; 311 men with cardiovascular disease/diabetes were excluded.Primary and secondary outcome measuresIHD and all-cause mortality.Results579 men (11.8%) died due to IHD and 2628 (53.7%) from all-cause mortality. Similarities and differences in risk predictors were found between men with low (n=1219), medium (n=2636) and high (n=846) physical work demands. After control for potential confounders, high physical fitness conferred a reduced risk of IHD mortality only among men with high physical work demands (HR: 0.48, 95% CI 0.24 to 0.96), a moderate/high level of leisure-time physical activity was associated with reduced risk of IHD mortality only among men with moderate and high physical work demands. High systolic blood pressure and smoking were risk factors in all groups. Similar, but less pronounced differences in risk factors for all-cause mortality between groups were found.ConclusionsThe risk factors for IHD and all-cause mortality, low physical fitness and low leisure-time physical activity are not identical for men with different physical work demands. Preventive initiatives for IHD should be tailored to the physical work demands.
Breast cancer survival and season of surgery: an ecological open cohort study
Authors: Teilum Dorthe , Bjerre Karsten D , Tjønneland Anne M , Kroman Niels 
Published: January 2012

BackgroundVitamin D has been suggested to influence the incidence and prognosis of breast cancer, and studies have found better overall survival (OS) after diagnosis for breast cancer in summer–autumn, where the vitamin D level are expected to be highest.ObjectiveTo compare the prognostic outcome for early breast cancer patients operated at different seasons of the year.DesignOpen population-based cohort study.SettingDanish women operated 1978–2010.Cases79 658 adjusted for age at surgery, period of surgery, tumour size, axillary lymph node status and hormone receptor status.Statistical analysisThe association between OS and season of surgery was analysed by Cox proportional hazards regression models, at survival periods 0–1, 0–2, 0–5 and 0–10 years after surgery. A two-sided p value <0.05 was considered statistical significant.ResultsOnly after adjustment for prognostic factors that may be influenced by vitamin D, 1-year survival was close to significantly associated season of surgery. 2, 5 and 10 years after surgery, the association between OS and season of surgery was not significant.LimitationsSeason is a surrogate measure of vitamin D.ConclusionsThe authors found no evidence of a seasonal variation in the survival after surgery for early breast cancer. Lack of seasonal variation in this study does not necessarily mean that vitamin D is of no importance for the outcome for breast cancer patients.
Hearing in 44–45 year olds with m.1555A>G, a genetic mutation predisposing to aminoglycoside-induced deafness: a population based cohort study
Authors: Rahman Shamima , Ecob Russell , Costello Harry , Sweeney Mary G , Duncan Andrew J , Pearce Kerra , Strachan David , Forge Andrew , Davis Adrian , Bitner-Glindzicz Maria 
Published: January 2012

BackgroundThe mitochondrial DNA mutation m.1555A>G predisposes to permanent idiosyncratic aminoglycoside-induced deafness that is independent of dose. Research suggests that in some families, m.1555A>G may cause non-syndromic deafness, without aminoglycoside exposure, as well as reduced hearing thresholds with age (age-related hearing loss).ObjectivesTo determine whether adults with m.1555A>G have impaired hearing, a factor that would inform the cost–benefit argument for genetic testing prior to aminoglycoside administration.DesignPopulation-based cohort study.SettingUK.ParticipantsIndividuals from the British 1958 birth cohort.MeasurementsHearing thresholds at 1 and 4 kHz at age 44–45 years; m.1555A>G genotyping.Results19 of 7350 individuals successfully genotyped had the m.1555A>G mutation, giving a prevalence of 0.26% (95% CI 0.14% to 0.38%) or 1 in 385 (95% CI 1 in 714 to 1 in 263). There was no significant difference in hearing thresholds between those with and without the mutation. Single-nucleotide polymorphism analysis indicated that the mutation has arisen on a number of different mitochondrial haplogroups.LimitationsNo data were collected on aminoglycoside exposure. For three subjects, hearing thresholds could not be predicted because information required for modelling was missing.ConclusionsIn this cohort, hearing in those with m.1555A>G is not significantly different from the general population and appears to be preserved at least until 44–45 years of age. Unbiased ascertainment of mutation carriers provides no evidence that this mutation alone causes non-syndromic hearing impairment in the UK. The findings lend weight to arguments for genetic testing for this mutation prior to aminoglycoside administration, as hearing in susceptible individuals is expected to be preserved well into adult life. Since global use of aminoglycosides is likely to increase, development of a rapid test is a priority.