bluuebunny/crossref_metadata_2025 huggingface dataset:
The Clinical Significance of Aspirin Resistance in Patients With Chest Pain
Authors: Aydinalp Alp , Atar Ilyas , Gulmez Oyku , Atar Asli , Acikel Sadik , Bozbas Huseyin , Ozgul Aliseydi , Ertan Cagatay , Ozin Bulent , Muderrisoglu Haldun
Published: March 2010

Background

There are conflicting data in the literature about the clinical significance of aspirin resistance.

Hypothesis

We aimed to prospectively evaluate the prevalence of biochemical aspirin resistance in patients on aspirin therapy who were admitted to the emergency clinic with chest pain. We also aimed to evaluate the relation between acute coronary syndromes (ACS) and aspirin resistance.

Methods

A total of 338 patients were included in the study. Platelet reactivity was measured with the PFA‐100 system (Dade Behring Inc, Deerfield, IL). Aspirin resistance determined by the PFA‐100 was defined as a normal collagen and/or epinephrine closure time despite aspirin treatment (<165 s).

Results

Patients were divided into 4 groups: stable angina pectoris (SAP), unstable angina/non‐ST‐elevation myocardial infarction (UA/NSTEMI), ST‐elevation myocardial infarction (STEMI), and rule out ACS. Aspirin resistance was found in 81 (24%) patients in all groups. Patients with ACS had significantly more aspirin resistance than patients with rule out ACS or patients with SAP (P < .001). In the SAP group, 31 (19.6%) patients; in the UA/NSTEMI group, 19 (35.8%) patients; in the STEMI group, 14 (50%) patients; and in the rule out ACS group, 17 (17.2%) patients had aspirin resistance (P < .001). In the multivariate analysis, cardiac biomarker elevation on admission to emergency department and platelet count appeared as independent factors predictive of aspirin resistance.

Conclusions

We demonstrated that incidence of aspirin resistance was significantly higher in patients who were finally diagnosed as ACS, especially in aspirin‐taking patients admitted to the emergency clinic with STEMI. Copyright © 2010 Wiley Periodicals, Inc.
TGF‐β1 Expression and Atrial Myocardium Fibrosis Increase in Atrial Fibrillation Secondary to Rheumatic Heart Disease
Authors: Xiao Hua , Lei Han , Qin Shu , Ma Kanghua , Wang Xi
Published: March 2010

Background:

Atrial fibrosis was considered a structural basis for the development and sustaining of atrial fibrillation (AF). Transforming growth factor‐β1 (TGF‐β1) was one of the main factors for accelerating collagen production. The contribution of TGF‐β1 in the pathogenesis of AF needs further investigation.

Hypothesis:

The altered expression and distribution of TGF‐β1 will be associated with the changes in atrial fibrosis in different types of AF patients with rheumatic heart disease (RHD).

Methods:

Right atrial specimens obtained from 38 RHD patients undergoing mitral valve replacement surgery were divided into 3 groups: the sinus rhythm group (n = 8), the paroxysmal AF group (pAF; n = 10), and the chronic AF group (cAF; AF lasting ≥ 6 mo; n = 20). The degree of atrial fibrosis, collagen content, serum levels, messenger RNA (mRNA), and protein expression of TGF‐β1 were detected.

Results:

The collagen content, serum level, TGF‐β1 mRNA, and protein expression of the atrial tissue increased gradually in sinus rhythm, for both pAF and cAF groups, respectively. A positive correlation between TGF‐β1 and the degree of atrial fibrosis was also demonstrated (P < 0.05).

Conclusion:

The TGF‐β1 expression in atrial tissue increased gradually in proportion to the degree of atrial fibrosis in AF and was associated with the type of AF, which suggests that TGF‐β1 is possibly involved in the pathogenesis of AF in RHD patients. Copyright © 2010 Wiley Periodicals, Inc.
Acute ST‐elevation Myocardial Infarction in Young Patients: 15 Years of Experience in a Single Center
Authors: Chua Su‐Kiat , Hung Huei‐Fong , Shyu Kou‐Gi , Cheng Jun‐Jack , Chiu Chiung‐Zuan , Chang Che‐Ming , Lin Sheng‐Chang , Liou Jer‐Young , Lo Huey‐Ming , Kuan Peiliang , Lee Shih‐Huang
Published: March 2010

Background:

There have been few studies done regarding young patients with ST‐elevation myocardial infarction (STEMI). The purpose of this study was to investigate the clinical characteristics and coronary angiographic features in young patients with STEMI.

Methods:

We collected data on 849 consecutive patients with STEMI from 1992 to 2006. Baseline clinical characteristics, coronary anatomy, and outcome were compared in young (≤45 yrs) and older patients (>45 yrs).

Results:

Young patients presented 11.6% of all patients with STEMI. These patients were predominantly male (92.9% vs 80.3%, P < 0.001), more likely to smoke (75.8% vs 47.2%, P < 0.001), obese (48.2% vs 27.9%, P = 0.002), have higher triglyceride levels (176.9 ± 153.8 mg/dL vs 140.7 ± 112.7 mg/dL, P = 0.005), and lower high‐density lipoprotein cholesterol (37.1 ± 7.9 mg/dL vs 42.8 ± 14.3 mg/dL, P = 0.005) than older patients. Also, younger patients had a shorter hospital stay (7.1 ± 4.9 d vs 8.5 ± 6.7 d, P = 0.04), less in‐hospital morbidity (29.3% vs 39.7%, P = 0.02), and mortality (3.0% vs 12.3%, P = 0.002). Killip class III or IV could predict in‐hospital morbidity and mortality in young patients. Both groups had similar rates of repeated percutaneous coronary intervention (PCI; 45.5% vs 41.5%, P = 0.23) and reinfarction (6.1% vs 3.2%, P = 0.32). Mortality rate during follow‐up was significantly lower in younger patients (3.0% vs 19.6%, P < 0.001).

Conclusion:

Cigarette smoking, obesity, and dyslipidemia were the most important modifiable risk factors in young patients with STEMI. These patients had a better outcome than older patients without differences in repeated PCI and reinfarction between them. Only Killip class III or IV could predict in‐hospital morbidity and mortality in young patients with STEMI. Copyright © 2010 Wiley Periodicals, Inc.
Recurrence of Acute Myocardial Infarction in Patients Discharged on Clopidogrel and a Proton Pump Inhibitor After Stent Placement for Acute Myocardial Infarction
Authors: Evanchan Jason , Donnally Michael R. , Binkley Philip , Mazzaferri Ernest
Published: March 2010

Background:

The purpose of this study was to determine the readmission rate for acute myocardial infarction (AMI) in patients discharged on clopidogrel and a proton‐pump inhibitor (PPI) versus patients discharged on clopidogrel alone after experiencing an AMI and undergoing stent placement. Clopidogrel is a prodrug that requires metabolism in the liver by the cytochrome P450 system (CYP450), in particular cytochrome P450 2C19 (CYP2C19).1 Recent studies have suggested that medications metabolized by CYP450, such as PPIs, influence the effect of clopidogrel on platelet function2,3 with an increased risk of cardiovascular events.4,5 PPIs are often administered with clopidogrel due to the increased bleeding risk of dual antiplatelet therapy, a strategy endorsed by existing consensus guidelines.6

Hypothesis:

Treatment with a PPI in combination with clopidogrel would increase the risk of readmission for an AMI after stent placement for AMI.

Methods:

We collected data on all patients discharged on clopidogrel after stent placement for an AMI between January 2003 and January 2008. Patients were followed for 1 year after their index hospitalization for readmission for an AMI. Rates of readmission were determined for those discharged on clopidogrel alone versus those discharged on clopidogrel and a PPI.

Results:

Patients discharged on clopidogrel and a PPI had higher rates of readmission for AMI within 1 year of stent implantation for AMI.

Conclusions:

Patients discharged on clopidogrel and a PPI, including esomeprazole and pantoprazole, seem to be at an increased risk of recurrent AMI within 1 year after stent placement for an AMI. Copyright © 2010 Wiley Periodicals, Inc.
Fibrinolysis Versus Primary Percutaneous Intervention in ST‐elevation Myocardial Infarction With Long Interhospital Transfer Distances
Authors: Beri Abhimanyu , Printz Mary , Hassan Ansar , Babb Joseph D.
Published: March 2010

Background:

Current guidelines recommend rapid initiation of reperfusion therapy for ST‐elevation myocardial infarction (STEMI), with short‐distance transfer for primary percutaneous coronary intervention (pPCI) preferred over fibrinolysis in non–pPCI‐capable hospitals. Comparative outcomes in patients with longer transfer times are unclear.

Hypothesis:

We designed this study to assess whether administering fibrinolytics prior to initiating longer‐distance interhospital transfer in patients with STEMI leads to a delay in transfer or worse outcomes compared with transfer for pPCI.

Methods:

We analyzed 259 STEMI patients transferred to a receiving pPCI‐capable center in eastern North Carolina. The patients were divided into 2 groups, with 43 (16.6%) transferred for pPCI and the remaining 216 (83.4%) transferred following fibrinolysis. The primary endpoint was door‐to‐door time. We also compared stroke, death, significant bleeding, and combined outcomes between the 2 groups.

Results:

The median door‐to‐door time was similar for pPCI and fibrinolysis patients (135 vs 128 minutes; P = 0.71). Median door‐to‐balloon time among pPCI patients was 182 minutes from the point of arrival at the referral hospital and 49 minutes from arrival at the receiving pPCI center. Median door‐to‐needle time in the fibrinolysis patients was 30 minutes, with rescue PCI eventually performed in 81 (37.5%) patients. In‐hospital mortality was higher in patients with pPCI (9.3%) compared with fibrinolysis patients (1.9%; P = 0.03). Combined incidence of stroke, significant bleeding, and death was 14% in pPCI patients compared with 7% in fibrinolysis patients (P = 0.13).

Conclusions:

In settings with longer transfer distances, administering fibrinolytics prior to transfer to a pPCI‐capable center did not cause any significant delay in transfer or worse outcomes. Copyright © 2010 Wiley Periodicals, Inc.
Physician Stated Atrial Fibrillation Management in Light of Treatment Guidelines: Data From an International, Observational Prospective Survey
Authors: Kowey Peter R. , Breithardt Günter , Camm John , Crijns Harry , Dorian Paul , Le Heuzey Jean‐Yves , Pedrazzini Laurence , Prystowsky Eric N. , Salette Geneviève , Schwartz Peter J. , Torp‐Pedersen Christian , Weintraub William
Published: March 2010

Background:

The Registry on Cardiac Rhythm Disorders Assessing the Control of Atrial Fibrillation (RecordAF) study is the first worldwide, prospective, survey of real‐life management of atrial fibrillation (AF) in recently diagnosed patients (n = 5604) with a 1‐year follow‐up.

Hypothesis:

Surveys of AF management have identified a divergence between guidelines and clinical practice, and an overinterpretation of guidelines in low‐risk patients.

Methods:

Physicians' theoretical approaches to rhythm and rate control were investigated using a pre‐study questionnaire.

Results:

One cardiologist, from each of the 583 sites in 6 regions, completed a questionnaire on their practice and management of AF patients. In AF patients with structural heart disease (SHD), amiodarone was the most frequent choice of first‐line rhythm control agents in all regions. Amiodarone or sotalol tended to be the preferred second‐line rhythm control agents, 1 exception being Central/South America. β‐Blockers were the first‐line rate control agents for patients with AF and SHD in all regions, and calcium channel blockers and cardiac glycosides were the most common second‐line rate control treatments in all regions, except Asia. In lone AF patients, propafenone (30.6%), flecainide (24.1%), and amiodarone (21.7%) were the most common global choices of first‐line rhythm control, and amiodarone or sotalol were the preferred second‐line rhythm control agents, 1 exception being Central/South America.

Conclusions:

These results highlight points of divergence from the American College of Cardiology (ACC)/ American Heart Association (AHA)/European Society of Cardiology (ESC) guidelines for the management of AF in terms of first‐line drug selection in patients with associated SHD or coronary artery disease. Copyright © 2010 Wiley Periodicals, Inc.
Magnetohydrodynamic Simulation of Tungsten Wire in Wire‐Array Z Pinch
Authors: Kim D.‐K. , Chittenden J. P. , Lebedev S. V. , Marocchino A. , Suzuki‐Vidal F.
Published: March 2010

The magnetohydrodynamic behavior of tungsten wire ablating in wire‐array Z pinch discharge on MAGPIE is simulated in a two‐dimensional fine‐grid domain using the GORGON code. A nonideal resistivity model has been implemented in the simulation to obtain plasma transport coefficients in the high density regime along with a screened hydrogenic model to calculate the radiative cooling. Starting from the initial state of warm dense plasma, the evolution of ablated wire is demonstrated to show its explosion and implosion dynamics as a function of discharge time and then the computed profile of electron density is compared with the contour lines reproduced from the measurement by a laser interferometer during the early stage of discharge. The comparison overall shows a fair agreement in terms of the magnitude and the profile shape while some discrepancies can be attributed to the simplified description of the internal wire core physics (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Runaway Electron Measurements in the EAST Tokamak
Authors: Lu H. W. , Hu L. Q. , Lin S. Y. , Wang S. F. , Zhong G. Q. , the HT‐7 team
Published: March 2010

An experimental study of runaway electrons in the EAST tokamak has been performed by a recently developed multi‐channel hard x‐ray diagnostics based on NaI(TL) scintillator detectors. It is found that in the current quench phase, the inductive loop voltage plays an important role in the generation of runaway electrons. And the avalanche mechanism was the main mechanism for runaway electrons after the disruptions. The distribution and transportation of runaway electrons were also investigated by multi‐channel hard x‐ray diagnostics. It is also found that the intensity of runaway electrons emission in the core plasma was much higher than those in the downside of the cross‐section, while the emission intensity of runaway electrons in the core plasma was almost the same. Calculated shrinking coefficient of runaway electrons emission after the plasma disruption was about 26 m/s according to the experimental data (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Effect of the Electron‐Beam Self‐Fields on Gain in an Optical Wiggler Pumped Free‐Electron Laser
Authors: Hasanbeigi A. , Mehdian H. , Jafari S.
Published: March 2010

The effects of self fields on gain for a free‐electron lasers (FELs) with electromagnetic‐wave wiggler and an axial guide magnetic field is presented. The relativistic equation of motion for a single electron for all relevant fields, including wiggler, self‐fields and axial guide magnetic field has been solved. Two classes of possible single‐particle trajectories in this configuration are found. Result of the numerical calculation shown that the relativistic part of group I (group II) orbits decreases (increases) monotonically with the axial field. The gain equations for the FEL configuration by adding the effect of self‐fields have been derived. The numerical calculation has been employed to analysis the gain induced by the effects of the self‐fields. It is shown that, for group I orbits the gain decreases in the presence of self‐fields and the gain decrement increases with increasing axial guide magnetic field, while for group II orbits the self‐fields enhances the gain. The gain decrement and enhancement are due to diamagnetic and paramagnetic effects of the self‐magnetic field, respectively. The comparison of the gain for electromagnetic‐wave wiggler with the gain in helical wiggler has been done (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Optical Properties of Model Moderately Coupled Plasmas
Authors: Arkhipov Yu. V. , Askaruly A. , Baimbetov F. B. , Ballester D. , Davletov A. E. , Meirkanova G. M. , Tkachenko I. M.
Published: March 2010

We review our approach to the modelling of optical properties of model moderately coupled plasmas. On the basis of the classical theory of moments the external and internal dynamic conductivities and the reflectivity coefficient of a model hydrogen moderately coupled plasma are determined using all known exact relations and sum rules. The sum rules which are the power frequency moments of the loss function are calculated using the Deutsch effective potential and the hypernetted chain equations. MD simulation data are used and numerical simulations are suggested (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Expression of seven members of the ADAM family in developing chicken spinal cord
Authors: Lin Juntang , Yan Xin , Markus Annett , Redies Christoph , Rolfs Arndt , Luo Jiankai
Published: March 2010

The expression patterns of seven members of the ADAM (a disintegrin and metalloprotease) family, including ADAM9, ADAM10, ADAM12, ADAM13, ADAM17, ADAM22, and ADAM23, were analyzed in the developing chicken lumbar spinal cord by in situ hybridization and immunohistochemistry. Results show that each individual ADAM is expressed and regulated spatiotemporally in the lumbar cord and its surrounding tissues. ADAM9, ADAM10, ADAM22, and ADAM23 are expressed predominantly by motoneurons in the motor column and by sensory neurons in the dorsal root ganglia, each with a different expression pattern. ADAM12 and ADAM13 are mainly expressed in the meninges around the lumbar cord and in the condensed sheets of chondroblasts around the vertebrae. ADAM17 expression is strong in the ventricular layer and limited to early stages. The differential expression of the ADAMs in the lumbar cord suggests that the ADAMs play a regulatory role in development of the spinal cord. Developmental Dynamics 239:1246–1254, 2010. © 2010 Wiley‐Liss, Inc.
Placodal sensory ganglia coordinate the formation of the cranial visceral motor pathway
Authors: Takano‐Maruyama Masumi , Chen Yiju , Gaufo Gary O.
Published: March 2010

The parasympathetic reflex circuit is controlled by three basic neurons. In the vertebrate head, the sensory, and pre‐ and postganglionic neurons that comprise each circuit have stereotypic positions along the anteroposterior (AP) axis, suggesting that the circuit arises from a common developmental plan. Here, we show that precursors of the VIIth circuit are initially aligned along the AP axis, where the placode‐derived sensory neurons provide a critical “guidepost” through which preganglionic axons and their neural crest‐derived postganglionic targets navigate before reaching their distant target sites. In the absence of the placodal sensory ganglion, preganglionic axons terminate and the neural crest fated for postganglionic neurons undergo apoptosis at the site normally occupied by the placodal sensory ganglion. The stereotypic organization of the parasympathetic cranial sensory–motor circuit thus emerges from the initial alignment of its precursors along the AP axis, with the placodal sensory ganglion coordinating the formation of the motor pathway. Developmental Dynamics 239:1155–1161, 2010. © 2010 Wiley‐Liss, Inc.
Temporal and spatial patterning of axial myotome fibers in Xenopus laevis
Authors: Krneta‐Stankic Vanja , Sabillo Armbien , Domingo Carmen R.
Published: March 2010

Somites give rise to the vertebral column and segmented musculature of adult vertebrates. The cell movements that position cells within somites along the anteroposterior and dorsoventral axes are not well understood. Using a fate mapping approach, we show that at the onset of Xenopus laevis gastrulation, mesoderm cells undergo distinct cell movements to form myotome fibers positioned in discrete locations within somites and along the anteroposterior axis. We show that the distribution of presomitic cells along the anteroposterior axis is influenced by convergent and extension movements of the notochord. Heterochronic and heterotopic transplantations between presomitic gastrula and early tail bud stages show that these cells are interchangeable and can form myotome fibers in locations determined by the host embryo. However, additional transplantation experiments revealed differences in the competency of presomitic cells to form myotome fibers, suggesting that maturation within the tail bud presomitic mesoderm is required for myotome fiber differentiation. Developmental Dynamics 239:1162–1177, 2010.© 2010 Wiley‐Liss, Inc.
Primer and interviews: Diverse connections between primary cilia and Hedgehog signaling
Authors: Kiefer Julie C.
Published: March 2010

On the surface, the Hedgehog (Hh) pathway and primary cilia make strange bedfellows. Hh is a dynamic regulator of a myriad of developmental processes, ranging from spinal cord and limb patterning to lung branching morphogenesis. By contrast, immotile primary cilia were long considered ancestral holdovers with no known function. Considering the disparate perceptions of these two phenomena, the relatively recent discovery that there is a symbiotic‐like relationship between Hh and cilia was unexpected. This primer covers the basics of primary cilia and Hh signaling, highlighting variations in ways they are connected across species, and also discusses the evolutionary implications of these findings. Roles of cilia in signal transduction are analyzed further in an interview with Søren T. Christensen, PhD, and Andrew S. Peterson, PhD, in the A Conversation With the Experts section. Developmental Dynamics 239:1255–1262, 2010. © 2010 Wiley‐Liss, Inc.
Metallo‐Controlled Dynamic Molecular Tweezers: Design, Synthesis, and Self‐Assembly by Metal‐Ion Coordination
Authors: Ulrich Sébastien , Petitjean Anne , Lehn Jean‐Marie
Published: March 2010

The introduction of controllable dynamic features into synthetic receptors represents a step towards “smart” adaptive nanodevices. We report herein our studies on the construction of dynamic molecular tweezers in which the binding of a substrate is allosterically controlled through shape switching of the receptor induced by metal‐ion coordination. 1D, 2D NMR spectroscopy and X‐ray crystallography were used to identify the nature of the metallosupramolecular entity generated. The presence of large aromatic naphthalene diimide moieties on the scaffold of the molecular tweezers strongly influences their coordination‐driven self‐assembly. It was found that these additional stacking interactions lead to the cooperative formation of a homocomplex, to the self‐sorted assembly of a hetero complex, and to the binding of non‐coordinating aromatic guests.
Fecal genotyping and contaminant analyses reveal variation in individual river otter exposure to localized persistent contaminants
Authors: Guertin Daniel A. , Harestad Alton S. , Ben-David Merav , Drouillard Ken G. , Elliott John E.
Published: March 2010

The present study investigated polyhalogenated aromatic hydrocarbon (PHAH) concentrations in feces of known river otters (Lontra canadensis) along the coast of southern Vancouver Island, British Columbia, Canada. Specifically, we combined microsatellite genotyping of DNA from feces for individual identification with fecal contaminant analyses to evaluate exposure of 23 wild otters to organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs), and polybrominated diphenylethers (PBDEs). Overall, feces collected from otters in urban/industrial Victoria Harbor had the greatest concentrations of nearly all compounds assessed. Fecal concentrations of OCPs and PBDEs were generally low throughout the region, whereas PCBs dominated in all locations. Re-sampling of known otters over space and time revealed that PCB exposure varied with movement and landscape use. Otters with the highest fecal PCB concentrations were those inhabiting the inner reaches of Victoria Harbor and adjacent Esquimalt Harbor, and those venturing into the harbor systems. Over 50% of samples collected from eight known otters in Victoria Harbor had total-PCB concentrations above the maximum allowable concentration as established for Eurasian otter (Lutra lutra) feces, with a geometric mean value (10.6 mg/kg lipid wt) that exceeded the reproductive toxicity threshold (9 mg/kg lipid wt). Those results are consistent with our findings from 1998 and 2004, and indicate that the harbors of southern Vancouver Island, particularly Victoria Harbor, are a chronic source of PCB exposure for otters. The present study further demonstrates the suitability of using otter feces as a noninvasive/destructive biomonitoring tool in contaminant studies, particularly when sampling of the same individuals at the local population-level is desired. Environ. Toxicol. Chem. 2010;29:275–284. © 2009 SETAC
Estimating the acute toxicity of waterborne chemicals in trout from measurements of median lethal dose and the octanol-water partition coefficient
Authors: Hodson Peter V. , Dixon D. George , Kaiser Klaus L. E.
Published: March 2010

Measurements of the median lethal dose (LD50) of chemicals to fish provide a simpler, faster and less expensive alternative to median lethal concentrations (LC50s). Since dose is controlled, LD50s may be a better basis for structure-activity relationships. However, LC50s are used extensively in aquatic hazard assessments. Therefore, LC50s and LD50s for rainbow trout of 48 organic chemicals were measured to determine whether LC50 could be predicted from LD50. A simple linear regression of log-transformed data provided the best fit (r = 0.70), but it accounted for only 50% of the variability in LC50s. LC50s were also strongly correlated with measures of molecular size [molecular weight (MW; r = −0.90) and Parachor (r = −0.89)] and of water-lipid partitioning [octanol-water partition coefficient (Kow; r = −0.73)]. Hence, inclusion of these factors in a multiple regression analysis was examined. Since MW and Parachor were negatively correlated with LD50 (r = −0.61 and −0.60, respectively), they were not true independent variables and were not used. However, there was no relationship of Kow with LD50, and a multiple regression analysis using both LD50 and Kow predicted LC50 with greater certainty (r = 0.92) than did either factor alone. Therefore, LC50 can be predicted from LD50 when partitioning of a chemical from water to lipid is recognized.
QSAR investigation of benzene toxicity to fathead minnow using molecular connectivity
Authors: Hall Lowell H. , Maynard Ellen L. , Kier Lemont B.
Published: March 2010

The topological methods of molecular connectivity and kappa shape analysis have been applied to a set of 65 substituted benzenes and their toxicities to fathead minnow Pimephales promelas. The three variables 1χ, 1kα and 6χvp along with an ortho/para-dinitro indicator variable yield a QSAR equation with r = 0.940, s = 0.26 and F = 114. This equation is then used to estimate toxicities for 22 compounds not in the original data set. Twelve of the predicted compounds contain substituents in the original data set but 10 contain substituents new to the data, including fluoro-, cyano- and acyl-.
Modeling the fate of chemicals in an aquatic environment: The use of computer spreadsheet and graphics software
Authors: Southwood Jeanette M. , Harris Reed C. , MacKay Don
Published: March 2010

The Quantitative Water Air Sediment Interaction (QWASI) model, based on the concept of fugacity, is used to develop quantitative descriptions of the fate of chemicals in aquatic environments using LOTUS 1-2-3 software on a microcomputer. This software package is shown to provide a powerful, easy to use framework in which to use QWASI to simulate the reported fate of three chemicals: tertiary butylphenyl diphenyl phosphate, 3,4-dichloroaniline and chloroform. For each chemical, the graphics capabilities and interactive features of LOTUS 1-2-3 are used to guide the modeler regarding the influence of various processes on the fate of the chemical and determine appropriate variables on which to focus to improve the simulation.
Identification of ammonia as an important sediment-associated toxicant in the lower fox River and green bay, Wisconsin
Authors: Ankley Gerald T. , Katko Albert , Arthur John W.
Published: March 2010

Toxicity of sediment pore water from 13 sites in the lower Fox River/Green Bay watershed was assessed using a number of test species. Sediment pore water from the 10 lower Fox River sites exhibited acute toxicity to fathead minnows (Pimephales promelas) and Ceriodaphnia dubia, and pore water samples from all 13 sites were chronically toxic to C. dubia. Sediment pore water from seven of the sampling sites was toxic to Selenastrum capricornutum, but none of the samples were toxic to Photobacterium phosphoreum. Toxicity characterization, identification and confirmation procedures indicated that a significant amount of the acute toxicity of the pore water to fathead minnows and C. dubia was due to ammonia. The identification of ammonia, a naturally occurring compound in sediments, as a potentially important sediment-associated toxicant has implications for sediment toxicity assessment and control, not only in the Fox River and Green Bay, but in other freshwater and marine systems as well.
The effects of nine diet and water combinations on the culture health ofCeriodaphnia dubia
Authors: Patterson Paul W. , Dickson Kenneth L. , Waller William T. , Rodgers John H.
Published: March 2010

Culture health of Ceriodaphnia dubia was evaluated for organisms cultured with all combinations of three foods and three waters. The criteria used to assess health of cultures included adult and neonate weights, time required to produce first broods, neonate production, adult survival, and resistance to hexavalent chromium. Diet-water combinations that produced the most neonates were not found to produce adults that were more resistant to chromium than those that produced fewer neonates. Of those evaluated, a diet of Selenastrum capricornutum and a yeast-trout food-cereal leaf mixture was best for culturing and testing Ceriodaphnia. The best tested synthetic culture water was a mixture of nine parts reconstituted hard water and one part bottled mineral water.
Comparison of microbial trophic interactions in aquatic microcosms designed for the testing of introduced microorganisms
Authors: Kroer Niels , Coffin Richard B. , Jørgensen Niels O.G.
Published: March 2010

Two aquatic microcosms of different complexity were calibrated with a eutrophic lake. The simple microcosm consisted of an intact sediment core with overlying water. The complex microcosm was compartmentalized (phytoplankton tank, grazer tank, and sediment cores) to allow manipulation of individual components of the microbial food web. The comparison showed that whereas average phytoplankton biomass and productivity were approximately 30% lower in microcosms, biomass and activity of the heterotrophs (bacteria and nanoflagellates) were equal to or higher (up to 40% higher) than the corresponding field values. Important components of the microbial loop were represented in both microcosms. In the field and simple microcosm, approximately 30% of the phytoplankton production was cycled through the microbial loop, whereas close to 50% was fluxed through the loop in the complex model. Similarly, bacterial production amounted to almost the same fraction of the primary production in the simple microcosm and the field (16 and 18%, respectively) but 29% in the complex model. The percentage of the primary production that ended up as nanoflagellate production, on the other hand, was almost similar in all systems (0.4%). These data indicate that while the simple microcosm was the better surrogate of the field, variability between replicate microcosms of the complex model was lower (10-25% and 25-41 % for the complex and simple models, respectively). The choice of model, therefore, depends on the questions asked. The results suggest that the trophic-level analysis is useful in calibration studies of microcosms intended for testing of microorganisms.
Purification of the 70-kDa heat-shock protein from catfish liver: Immunological comparison of the protein in different fish species and its potential use as a stress indicator
Authors: Abukhalaf Imad K. , Zimmerman Earl G. , Dickson Kenneth L. , Masaracchia Ruthann A. , Donahue Manus J. , Covington Sean
Published: March 2010

The heat-shock protein or stress-70 family was isolated from catfish liver. The homogeneity of the purified protein was analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Fish subjected to whole-body hyperthermia contained the constitutive and the heat-inducible stress-70 with approximate molecular weights of 70 and 68 kDa, respectively. The final purification product from livers of catfish raised under normal temperature was only the constitutive stress-70. Western blot analysis with rabbit antiserum prepared against purified catfish (Ictalurus punctatus) liver stress-70 showed that the antibody cross-reacted with liver, muscle, and gill tissue homogenates of fathead minnows (Pimephales promelas), red shiners (Cyprinella lutrensis), black bass (Micropterus salmoides), and bluegill (Lepomis macrochirus), with various intensities suggesting that stress-70s from different tissues of various fish species share common antigenic determinants of the protein. This substantiates that the antigen/antibody approach of stress-70 is useful as a stress indicator and, consequently, as a potential biomarker for water quality.
Ratios between acute aquatic toxicity and effects on population growth rates in relation to toxicant mode of action
Authors: Roex Erwin W M , Van Gestel Cornelis A M , Van Wezel Annemarie P , Van Straalen Nico M
Published: March 2010

Environmental risk assessment of chemicals is mostly based on the results of standardized toxicity tests. To obtain environmental quality criteria, extrapolation factors are used that depend on the amount and quality of available data. These extrapolation factors do not, however, take into account the mode of action of the compound tested or the life history of the test organism. In this study, we analyzed the variability in acute-to-chronic ratios (ACRs) for various chemicals in relation to their mode of action. Chemicals were classified as nonpolar narcotics, polar narcotics, specifically acting compounds, and heavy metals. As an acute endpoint, the LC50 was used; as a chronic endpoint, the lowest test concentration at which the natural rate of population increase (r) is affected, or LOEC(r), was used. Data were derived from the on-line literature. Nonpolar narcotic chemicals demonstrate the smallest variation in ACRs, and acute tests can be used to derive chronic endpoints for this class. For the other classes, the variation in ACRs is larger. Fish species especially show a relatively large ACR. For heavy metals, differences in the mode of action may play an important role in explaining differences in ACRs. For the other three classes, however, it is less reliable to predict chronic toxicity using the results of acute tests. In general, differences in species sensitivity rather than in mode of action for the chemical seem to determine differences in ACRs.
Toxicity of Anacostia River, Washington, DC, USA, sediment fed to mute swans (Cygnus olor)
Authors: Beyer W Nelson , Day Daniel , Melancon Mark J , Sileo Louis
Published: March 2010

Sediment ingestion is sometimes the principal route by which waterfowl are exposed to environmental contaminants, and at severely contaminated sites waterfowl have been killed by ingesting sediment. Mute swans (Cygnus olor) were fed a diet for 6 weeks with a high but environmentally realistic concentration (24%) of sediment from the moderately polluted Anacostia River in the District of Columbia, USA, to estimate the sediment's toxicity. Control swans were fed the same diet without the sediment. Five organochlorine compounds were detected in the treated diets, but none of 22 organochlorine compounds included in the analyses was detected in livers of the treated swans. The concentrations of 24 polynuclear aromatic hydrocarbons measured in the treated diet were as high as 0.80 mg/kg, and they were thought to have been responsible for the observed induction of hepatic microsomal monooxygenase activity in livers. A concentration of 85 mg/kg of lead in the diet was enough to decrease red blood cell ALAD activity but was not high enough to cause more serious effects of lead poisoning. The dietary concentrations of Al, Fe, V, and Ba were high compared to the concentrations of these elements known to be toxic in laboratory feeding studies. However, the lack of accumulation in the livers of the treated swans suggested that these elements were not readily available from the ingested sediment. We did not study all potential toxic effects, but, on the basis of those that we did consider, we concluded that the treated swans were basically healthy after a chronic exposure to the sediment.
Formation of copper complexes in landfill leachate and their toxicity to zebrafish embryos
Authors: Fraser Jonathon K , Butler Catherine A , Timperley Michael H , Evans Clive W
Published: March 2010

Toxic metal organic complexeshavenot been found in natural waters, although someorganicacids form bioavailable lipophilic and metabolite-type metal complexes. Landfill leachates usually contain organic acids and in the urban environment these leachates, when mixed with storm waters containing Cu, could be a source of toxic Cu organic complexes in streams and estuaries. We investigated the formation of Cu complexes in the leachate from an active urban landfill and found that some of the complexes formed were toxic to zebrafish embryos. High and low nominal molecular weight (NMWT) fractions; >5,000 Da and <700 Da, of leachate both formed Cu complexes with almost identical Cu complexing characteristics but the toxicity was due solely to the low NMWT complexes formed in the <700 Da fraction. Chemical equilibrium modelling with MINTEQA2 and H and Cu complex conditional association constants and ligand concentrations obtained from pH and Cu titrations with a Cu ion-selective electrode and van den Berg–Ruzic analyses of the titration data was used to calculate the copper speciation in the embryo test solutions. This calculated speciation, which was confirmed by measurements of Cu2+ in the test solutions, enabled the toxicity due to the free Cu ion and to the Cu complexes to be distinguished.
Utility of organophosphorus hydrolase for the remediation of mutagenicity of methyl parathion
Authors: Cho Tae-Hyeon , Wild James R , Donnelly Kirby C
Published: March 2010

The pesticide methyl parathion (MP) is widely distributed in the environment and is chemically similar to nerve agents used in chemical warfare. Detoxification of this class of compounds is a critical environmental concern. Toxicity of MP is primarily associated with the inhibition of cholinesterase activity and resulting effects on the nervous system. Methyl parathion can also induce a genotoxic effect in bacterial and mammalian cells. However, the major metabolite of MP degradation, p-nitrophenol (PNP), is generally considered less toxic. This study reports on the evaluation of the genotoxic effect of MP, PNP, and a 1:1 MP:PNP mixture, and the utility of an organophosphorus hydrolase (OPH) enzyme for degradation of MP. Although MP induced a positive genotoxic response in Salmonella typhimurium TA100 at a dose of 1,000 μg per plate, PNP and a 1:1 mixture of PNP and MP did not induce a positive response. Methyl parathion dissolved in Luria-Bertani broth containing 5% methanol was treated with genetically engineered intact Escherichia coli cells expressing OPH activity. Significant rates of MP biodegradation were observed in the liquid culture. Within 55 h, an average 95.5% of the MP was converted to PNP as measured spectrophotometrically. The genotoxic potential of extracts of OPH-treated and untreated MP-amended media was measured with S. typhimurium strain TA100. The untreated media induced a dose-dependent genotoxic response at a dose equivalent to 54 ml of medium (MP 0.025 mg/ml) per plate, whereas the OPH-treated media failed to induce a genotoxic response. Chemical analysis indicated that about 90% of MP was removed from the media by treatment with OPH enzyme. These studies indicate that the OPH enzyme is capable of degrading MP and eliminating its genotoxic potential in liquid culture.
Evaluation of the efficacy of extrapolation population modeling to predict the dynamics ofAmericamysis bahiapopulations in the laboratory
Authors: Kuhn Anne , Munns Wayne R , Champlin Denise , McKinney Richard , Tagliabue Mark , Serbst Jonathan , Gleason Timothy
Published: March 2010

An age-classified projection matrix model has beendeveloped to extrapolate the chronic (28–35 d) demographic responses of Americamysis bahia (formerly Mysidopsis bahia) to population-level response. This study was conducted to evaluate the efficacy of this model for predicting the population behavior of A. bahia held (for more than three generations) under controlled laboratory exposure conditions. The research involved the performance of a standard life-cycle test and a multigenerational (greater than three mysid generations, 55 d) assay using A. bahia to experimentally evaluate model predictions regarding population-level risks of chemical exposure. The organic compound para-nonylphenol was chosen as the chemical stressor in these assays. This compound is a ubiquitous contaminant and suspected endocrine disruptor. Utilizing data obtained during the standard life-cycle test, aggregate estimates of population growth rate (λ) and measured p-nonylphenol concentration were used to develop an exposure-response model of population-level effects. These estimates provided the basis of predictions for the long-term dynamics of mysid populations exposed to p-nonylphenol. The veracity of the mysid population model was evaluated through quantitative comparisons of model predictions based on the life-cycle test with dynamics of the experimental populations (multigenerational assay results). The results indicate that the population model was able to project within a few micrograms per liter the concentration where population-level effects would begin to occur (projected 16 μg/L from the model vs measured 19 μg/L from the multigenerational assay).
Phenolic toxicity—detection and classification through the use of a recombinant bioluminescentEscherichia coli
Authors: Choi Sue Hyung , Gu Man Bock
Published: March 2010

A genetically engineered Escherichia coli strain, DPD2540, containing a fabA::luxCDABE fusion that gives a bioluminescent output when membrane fatty acids are limited was used to determine the extent to which phenolics result in the limitation of membrane fatty acids. Tested phenolics were found to be classifiable into two groups according to the bioluminescent response they elicited and their pKa. A dose-dependent bioluminescent response, due to fatty acid limitation, was seen for phenolics with pKa values greater than seven, which exist mainly in the protonated form (HA), while no significant bioluminescent response was seen, compared with the control, for phenolics with pKa values lower than seven, which exist almost entirely as A−. A newly modified distribution model for phenolic compounds in the cellular membrane is proposed and used to predict the bioluminescent response induced by group I phenolics and the cellular toxicity for both groups. The [HA]*, obtained with this model, shows good correlation with the various bioluminescent responses produced by group I phenolics. It was also found that the distribution ratio between the medium and the cell membrane, K1, calculated as well using the proposed model, is a good representative parameter for the cellular toxicity of the phenolic compounds according to their substituted groups when compared with the conventional method of using the octanol-water partition coefficient, log Kow. As a new parameter, the critical concentration was also shown to be a good representative of the cellular toxicity for group I phenolics to the Escherichia coli cells.
Mechanisms affecting the dissolution of nonaqueous phase liquids into the aqueous phase in slow-stirring batch systems
Authors: Schluep Mathias , Imboden Dieter M , Gälli René , Zeyer Josef
Published: March 2010

Understanding the kinetics of the exchange processes between nonaqueous phase liquids (NALs) and water is important in predicting the fate of anthropogenic compounds such as petroleum hydrocarbons, i.e., benzene, toluene, ethylbenzene, and xylene (BTEX) as well as polynuclear aromatic hydrocarbons (PAHs). Exchange processes occurring in the environment resemble the experimental setup of the slow-stirring method (SSM) designed to determine solubilities and octanol-water partition coefficients. Data obtained from SSM experiments for diesel fuel compounds are interpreted by a linear transfer model that is characterized by an aqueous molecular boundary layer and the water/NAPL equilibrium partition coefficient. For the chosen experimental setup, the boundary layer thickness is 2.42 × 10−2 cm. Typical equilibration times lie between 1 and 2 d. Due to the temperature dependence of the aqueous diffusivity, this time increases with decreasing temperature. Transport within the NAPL phase can slow down the exchange process for the more water-soluble compounds (e.g., benzene) provided that the stirring rate exceeds a critical value.
Sperm cell toxicity test using sea UrchinParacentrotus lividuslamarck (Echinodermata: Echinoidea): Sensitivity and discriminatory ability toward anionic and nonionic surfactants
Authors: Ghirardini Annamaria Volpi , Novelli Alessandra Arizzi , Likar Barbara , Pojana Giulio , Ghetti Pier Francesco , Marcomini Antonio
Published: March 2010

A reliable sperm cell toxicity test procedure has been developed for the Mediterranean sea urchin Paracentrotus lividus. The sensitivity and discriminatory ability of the test were investigated with regard to surfactants and their biotransformation products. Aromatic and aliphatic surfactants of anionic (linear alkylbenzene sulfonates [LAS]) and nonionic (alcohol polyethoxylates [AE] and nonylphenol polyethoxylates [NPE]) types and their aerobic biodegradation products, i.e., sulfophenylcarboxylates (SPC), polyethylene glycols (PEG), carboxylated polyethylene glycols (PEGC), carboxylated AE (AEC), and nonylphenol (NP), were examined in order to elucidate the influence of their molecular structure on toxicity. Experimental results reveal that the sperm cell test showed good discriminatory ability among all tested compounds, median effective concentration (EC50) values differing by about four orders of magnitude. The toxicity of anionic surfactants depends on the length of the alkyl chain and that of nonionic surfactants is due to their length and branching. Much lower toxicity was shown by aerobic biodegradation products in comparison with that of their parent compounds, with the exception of NP. The obtained EC50s were comparable with available literature data and constitute new toxicity data regarding surfactants for sea urchins.