bluuebunny/crossref_metadata_2025_split huggingface dataset:
Quantitative Structure Activity Relationships for Predicting the Bioaccumulation of POPs in Terrestrial Food‐Webs
Authors: Gobas Frank A. P. C. , Kelly Barry C. , Arnot Jon A. 
Published: May 2003

AbstractKOW based QSARs are used to assess the bioaccumulation potential of thousands of commercial chemicals in Canada and internationally. The QSARs, which are based on information from aquatic organisms, identify chemicals with a log KOW>5 to have a potential to biomagnify in food‐chains. This study investigates whether KOW based QSARs are also effective in identifying biomagnifying chemicals in terrestrial food‐chains. First, a terrestrial bioaccumulation model is developed and used to hypothesize the general relationship between the chemical's octanol‐air and octanol‐water partition and its biomagnification potential. Secondly, field observations of the bioaccumulation of persistent organic pollutants in wolves are used to test the hypothesis and explore the fundamental differences between QSARs for bioaccumulation in aquatic and terrestrial food‐chains. The results indicate that (i) QSARs for bioaccumulation in terrestrial food‐chains should include both octanol‐air (KOA) and octanol water partition coefficients (KOW); (ii) chemicals with a log KOA>approximately 5 can biomagnify in terrestrial food‐chains if log KOW>2 and the rate chemical transformation or metabolism is low; (iii) biomagnification factors in terrestrial food‐chains are much greater than those in aquatic food‐chains; (iv) biomagnification factors of very hydrophobic substances (log KOW>7) in terrestrial biota do not drop off with increasing KOW as has been observed in aquatic biota. The relevance of these findings is that current regulations and protocols may misidentify (i) low KOW but high KOA chemicals as having no bioaccumulation potential and (ii) very hydrophobic (log KOW>8.5) which appear not to biomagnify in aquatic organisms but have the potential to biomagnify in terrestrial food‐chains. Considering that 67.9% of the approximately 12 000 organic chemicals on Canada's Domestic Substances List exhibit high KOA but low KOW, this represents a major gap in our methods for screening bioaccumulative substances.
A Generic QSAR for Assessing the Bioaccumulation Potential of Organic Chemicals in Aquatic Food Webs
Authors: Arnot Jon A. , Gobas Frank A. P. C. 
Published: May 2003

AbstractThis study presents the development of a quantitative‐structure activity relationship (QSAR) for assessing the bioaccumulation potential of organic chemicals in aquatic food webs. The QSAR is derived by parameterization and calibration of a mechanistic food web bioaccumulation model. Calibration of the QSAR is based on the derivation of a large database of bioconcentration and bioaccumulation factors, which is evaluated for data quality. The QSAR provides estimates of the bioaccumulation potential of organic chemicals in higher trophic level fish species of aquatic food webs. The QSAR can be adapted to include the effect of metabolic transformation and trophic dilution on the BAF. The BAF‐QSAR can be applied to categorize organic chemical substances on their bioaccumulation potential. It identifies chemicals with a log KOW between 4.0 and 12.2 to exhibit BAFs greater than 5 000 in the absence of significant metabolic transformation rates. The BAF‐QSAR can also be used in the derivation of water quality guidelines and total maximum daily loadings by relating internal concentrations of organic chemicals in upper trophic fish species to corresponding concentrations in the water.
Improving Opportunities for Regulatory Acceptance of QSARs: The Importance of Model Domain, Uncertainty, Validity and Predictability
Authors: Walker John D. , Carlsen Lars , Jaworska Joanna 
Published: May 2003

AbstractFor Quantitative Structure Activity Relationships (QSARs) to be accepted by the regulated and regulatory communities, their scope for use needs to be agreed upon by government and industry. This paper discusses the importance of model domain, uncertainty, validity and predictability assessment in promoting the regulatory acceptance of QSARs.
Verification of literature‐derived SARs for skin irritation and corrosion
Authors: Hulzebos E. M. , Maslankiewicz L. , Walker J. D. 
Published: May 2003

AbstractStructural features known to irritate and corrode skin and physical properties associated with skin absorption were used to evaluate the irritation and corrosion potential of chemicals. Chemicals that irritate and corrode skin include organic acids and bases, aldehydes, halogenated esters, and chemicals with reactive groups. The activity of the reactive group decreases when sterically hindered by adjacent substituents or when electrons of the reactive group interfere with electrons of adjacent substituents. The structural features presented are a good basis for the calculation of SAR prediction rules. Also quantitative and qualitative physical conditions are given to predict skin irritation and skin corrosion.
QSAR Prediction of Ozone Tropospheric Degradation
Authors: Gramatica Paola , Pilutti Pamela , Papa Ester 
Published: May 2003

AbstractThe lifetime of organic chemicals in the atmosphere can be calculated from a knowledge of the rate constant of their reaction with free radicals (OH., NO3.) and O3. The rate constant for the tropospheric degradation of 125 organic compounds by reaction with ozone, the least widely and successfully modelled degradation process, is predicted here by MLR‐QSAR modelling based on a variety of theoretical molecular descriptors, selected by the Genetic Algorithm‐Variable Subset Selection (GA‐VSS) procedure. The proposed models, checked for their reliability and robustness, have good predictivity, verified by internal (Q2LMO(50%)=82–88%) and also external validation (Q2EXT =90%). The best splitting of the original data set into representative training and test sets has been obtained by the Experimental Design approach. The model applicability domain was always verified by the leverage approach. The average root‐mean square error (RMS) for the prediction of log kO3 was 0.73, similar to the typical range of experimental error.
QSAR Modeling of Bioconcentration Factor by theoretical molecular descriptors
Authors: Gramatica Paola , Papa Ester 
Published: May 2003

AbstractBioconcentration factor (BCF) is an important ecotoxicological parameter describing the tendency of chemical concentration in organisms, mainly aquatic. Log BCF of 238 non‐ionic organic compounds was modelled by multiple linear regression models, using theoretical structural descriptors of different kinds (1D‐, 2D‐ and 3D‐) selected by the Genetic Algorithm procedure. The models, validated for their predictivity using internal (Q2, Q2LMO) and external validations (Q2EXT) can be applied for the prediction of not available data, and also for not yet synthesized compounds. Comparison of the proposed models and log Kow‐ or molecular connectivity (MCIs)‐based models reveals that our approach is more predictive than the log Kow‐based model and also simpler than the MCIs‐based model.
Using HPV Chemical Data to Develop QSARs for Non‐HPV Chemicals: Opportunities to Promote More Efficient Use of Chemical Testing Resources
Authors: Walker John D. , Dimitrov Sabcho , Mekenyan Ovanes 
Published: May 2003

AbstractThere are opportunities to use data developed for High Production Volume (HPV) chemicals to save chemical testing resources for non‐HPV chemicals. First, data being developed for HPV chemicals could reduce chemical testing resources for non‐HPV chemicals, if the data can be used to develop and validate Quantitative Structure Activity Relationships (QSARs) that can be used to make predictions for non‐HPV chemicals. Second, strategies need to be developed to identify chemicals for which QSARs may not make reliable predictions and appropriate tests need to be conducted so that these and related chemicals can be included in more robust QSAR predictions. This paper illustrates the chemical testing resources that could be saved by using QSAR predictions and discusses guidelines and issues that need to be addressed before using data from HPV chemicals to develop QSARs for non‐HPV chemicals.
Simple prediction of atmospheric concentration of hydrophilic compounds based on the classification of industrial uses
Authors: Kishi Hideko , Sekine Yoshika 
Published: May 2003

AbstractVolatilization is a route of emission to an atmospheric compartment for chemicals. Although there are many good mathematical models for estimating the fate of volatile chemicals, agreement between the predicted and the measured concentration in air is not exactly evaluated because of the lack of emission factors and details on atmospheric chemistry. Moreover, available parameters are mostly limited for hydrophobic compounds. As a first step, authors investigated the relationship between annual production and atmospheric concentrations of volatile chemicals in the atmospheric monitoring data collected by the Ministry of Environment of Japan since 1974. Hydrophobic compounds were divided into two groups according to industrial uses: solvents/extraction agents and organic materials of chemical products. Significant linear regressions were found for both groups. The relationship between atmospheric concentrations of chemicals (Cair, ng/m3) against the amounts of annual production was expressed in logarithmic correlation equations; log Cair=1.32 log annual production −2.46, R2=0.70 and log Cair=0.72 log annual production −1.43, R2=0.92. The difference between the slopes may reflect emission factors of the processes. Then, these regression equations were applied to the 19 hydrophilic chemicals having OH, CHO, CO, COO, Oand (COOR)n inputting their annual production data. The predicted concentrations of such oxygenic compounds, if the industrial uses were determined, showed good agreement to the measured ones.
Pharmaceuticals and Personal Care Products in the Environment: Regulatory Drivers and Research Needs
Authors: Breton Roger , Boxall Alistair 
Published: May 2003

AbstractThe potential effect of human and veterinary medicines and other personal care products on the environment has become an important topic over the past few years. Whilst an assessment of the potential environmental risks posed by new and existing pharmaceuticals has been required in the United States (U.S.) for a number of decades, in the European Union (EU) and Canada assessments have only been required in the last 5–10 years. In the U.S., guidance has been available since the early 1980s on the assessment of veterinary medicines, whereas only recently has detailed guidance become available on how to perform the risk assessment in other areas. For example, in Canada, new pharmaceuticals (and other substances including novel foods, food additives, human biologics and genetic therapies, medical devices, natural health products, veterinary drugs, cosmetics) have been required to be notified for an environmental assessment under the Canadian Environmental Protection Act (CEPA 1999) since 2001. The European Medicines Evaluation Authority (EMEA) has published guidelines for assessment of veterinary medicines in use in Europe. For veterinary medicines attempts are currently being made by the Veterinary International Co‐operation on Harmonisation (VICH) to harmonise these approaches. Generally, the current assessment approaches are tiered and initially involve a comparison of environmental concentrations with set trigger values. If the trigger values are exceeded then a formal assessment has to be performed requiring data on environmental fate and ecotoxicity. Concerns have been raised over the current approaches used in each of the assessment processes and there are a number of areas that warrant further research. This paper will provide an overview of the regulatory assessment of pharmaceuticals and personal care products (PPCPs) and will expand on many of the topics for research in the future, and the role that QSAR scientists can play in this research will be highlighted.
Minimum binding energy and size of the doubly muonic T3 molecule
Authors: Eskandari M. R. , Faghihi F. 
Published: May 2003

AbstractThe minimum energy and size of doubly muonic T3 molecule in which two of the electrons are replaced by the much heavier muons are calculated by the well‐known variational method. The calculations show that the system possesses two minimum positions, one at a typically muonic distance and the second at the atomic distance. It is shown that at the muonic distance the effective charge, zeff, is 2.88. We assumed a symmetrical planar vibrational model between two minima and an oscillation potential energy is approximated in this region. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem 93: 377–383, 2003
Investigation of nucleoside analogs with anti‐HIV activity
Authors: Arissawa Márcia , Taft Carlton Anthony , Felcman Judith 
Published: May 2003

AbstractAlthough a relatively large number of drugs that inhibit human immunodeficiency syndrome (HIV)‐1 reverse transcriptase have been developed—such as AZT, d4T, ddI, 3TC, and ddC, which are chain terminating nucleoside analogs—resistance is still a major problem. Atomic charges, regioselective patterns of chemical reactivity, and other indices of biochemical activity may help us acquire a better understanding of how the drugs work and the mechanism of drug resistance. In this work, we investigated the above‐mentioned nucleoside analogs using the ab initio Hartree–Fock method with 3‐21G, 3‐21G*, 6‐31G, 6‐31G*, 6‐31G**, and 6‐31+G** basis sets as well as B3LYP/6‐31G**, including thus diffusion, polarization, and correlation effects to obtain fully optimized geometric parameters. Vibrational frequencies were calculated and we also investigated the effects of solvents, Mulliken, and natural bond orbital charge distribution, as well as hydrogen bond effects. We tried to correlate very low and very high anti‐HIV activity with charges, vibrational stretching frequencies, interatomic distances, and the effect of solvents. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem 93: 422–432, 2003
Gelatinisation Characteristics of Cassava Starch Settled in the Presence of Different Chemicals
Authors: Sajeev Moothandassery S. , Moorthy Subramoni N. , Kailappan Ramasami , Rani Vijayalekshmi Sunitha 
Published: May 2003

AbstractAddition of chemicals during the extraction of cassava starch for enhancing the settling rate, whiteness and compactness of the settled starch is an accepted commercial practice. The effect of addition of selected chemicals such as acids (sulphuric and hydrochloric acids), bleaching and oxidising agents (sodium metabisulphite and sodium hypochlorite) and alum during settling on the thermal and pasting properties of the cassava starch was examined. Treatment with sulphuric acid produced a noticeable increase in all DSC gelatinisation parameters, viz. onset gelatinisation temperature (To), temperature at peak minimum (Tp) and end temperature (Te), with increasing concentration of acid, while only a marginal shift could be obtained even at higher concentration of hydrochloric acid. However, no major effect resulted from treatment with sodium metabisulphite, sodium hypochlorite and alum. The gelatinisation enthalpy was hardly affected by the treatments. An exception was hydrochloric acid, which brought about a perceptible decrease in enthalpy at higher concentrations indicating that starch crystallinity is influenced to a small extent by hydrochloric acid. Pasting characteristics studied using a Rapid Visco Analyser showed that sulphuric acid, even at the lowest concentration (5 mM), considerably affected the structural characteristics of cassava starch, while hydrochloric acid induced similar effect only at higher concentrations. Alum reduced the paste viscosity while the bleaching agents (sodium metabisulphite and sodium hypochlorite) were not so effective in modifying the starch viscosity characteristics.
Cyclodextrins in the Textile Industry
Authors: Szejtli József 
Published: May 2003

AbstractIn the future cyclodextrins might play a significant role in the textile industry and might be used: (1) to remove surfactants from washed textiles; (2) to substitute surfactants; (3) in finishing textiles; (4) when bound chemically to fibers, to provide enhanced hydrophilicity and first of all, inclusion complex forming ability to immobilize perfumes, insect repellents, antimicrobial agents, etc.
Neurotoxic methamphetamine regimen severely impairs recognition memory in rats
Authors: Schröder Nadja , O'Dell Steven J. , Marshall John F. 
Published: May 2003

AbstractMethamphetamine (mAMPH), when administered repeatedly to rodents or primates, is neurotoxic to some cortical neurons and to forebrain dopaminergic and serotonergic axon terminals. The aim of the present study was to investigate the effects of a neurotoxic regimen of mAMPH on two hippocampus‐dependent memory tasks: object recognition, a nonspatial memory task, and the Morris water maze, a spatial memory task. Male rats were treated with mAMPH (4 × 4.0 mg/kg, s.c.) or saline and trained in the object recognition task 1 week and 3 weeks later. During training, animals explored two identical copies of the same object. In retention test sessions one of the objects was replaced by a novel object. mAMPH‐treated rats showed no recognition memory during the short‐term memory (STM) test, given 90 min after the training session, and showed marked impairments in the long‐term memory (LTM) test, given 24 h after training. Even 3 weeks after drug injections, the mAMPH‐treated animals were unable to discriminate between the novel and familiar objects during both STM and LTM tests. Despite the severe deficits observed in the recognition memory, no effects of prior mAMPH treatment were seen in the water maze task. Damage to monoamine terminals was confirmed by significant 30–40% losses of [125I]RTI‐55 binding to striatal dopamine transporter and hippocampal serotonin transporter sites at both 1 and 3 weeks after mAMPH treatments. Thus, administration of mAMPH restricted to a single day can produce a profound, persistent, and selective deficit in a nonspatial hippocampus‐dependent memory. Synapse 49:89–96, 2003. © 2003 Wiley‐Liss, Inc.
Blockade of neuronal facilitatory nicotinic receptors containing α3β2 subunits contribute to tetanic fade in the rat isolated diaphragm
Authors: Faria Miguel , Oliveira Laura , Timóteo M. Alexandrina , Lobo M. Graça , Correia‐de‐sá Paulo 
Published: May 2003

AbstractNicotinic receptor (nAChR) subtypes involved in pre‐ and postjunctional actions underlying tetanic fade were studied in rat phrenic‐nerve hemidiaphragms. We investigated the ability of subtype‐specific nAChR antagonists to depress nerve‐evoked contractions and [3H]‐acetylcholine ([3H]‐ACh) release. Muscle tension was transiently increased during brief high frequency trains (50 Hz for 5 sec). The rank potency order of nAChR antagonists to reduce tetanic peak tension was α‐bungarotoxin > d‐tubocurarine ≫ mecamylamine > hexamethonium. Reduction of maximal tetanic tension produced by dihydro‐β‐erythroidine (0.03–10 μM), methyllycaconitine (0.003–3 μM), and α‐conotoxin MII (0.001–0.3 μM) did not exceed 30%. Besides reduction of peak tension d‐tubocurarine (0.1–0.7 μM), mecamylamine (0.1–300 μM), and hexamethonium (30–3,000 μM) also caused tetanic fading. With α‐conotoxin MII (0.001–0.3 μM) and dihydro‐β‐erythroidine (0.03–10 μM), tetanic fade was evident only after decreasing the safety factor of neuromuscular transmission (with high magnesium ions, 6–7 mM). The antagonist rank potency order to reduce evoked (50 Hz for 5 sec) [3H]‐ACh release from motor nerve terminals was α‐conotoxin MII (0.1 μM) > dihydro‐β‐erythroidine (1 μM) ∼ d‐tubocurarine (1 μM) > mecamylamine (100 μM) > hexamethonium (1,000 μM). When applied in a concentration (0.3 μM) above that producing tetanic paralysis, α‐bungarotoxin failed to affect [3H]‐ACh release. Data obtained suggest that postjunctional neuromuscular relaxants interact with α‐bungarotoxin‐sensitive nicotinic receptors containing α1‐subunits, whereas blockade of neuronal α3β2‐containing receptors produce tetanic fade by breaking nicotinic autofacilitation of acetylcholine release. Synapse 49:77–88, 2003. © 2003 Wiley‐Liss, Inc.
Monocarboxylate transporters contribute to the adaptation of neuronal activity to repeated glucose deprivation in the rat lateral septal nucleus
Authors: Hasuo Hiroshi , Akasu Takashi 
Published: May 2003

AbstractUsing optical recording methods in the rat lateral septal nucleus (LSN) slice, we examined the question of whether antecedent hypoglycemia protects neurons from the adverse effects of subsequent hypoglycemic stimuli. The first exposure of LSN neurons to glucose deprivation for 15 min produced a marked depression of neuronal activity. The neuronal activity recovered by reapplication of glucose to the neurons. In neurons previously exposed to glucose deprivation, subsequent applications of glucose‐free artificial cerebrospinal fluid (ACSF) produced only weak depression of the neuronal activity. The contribution of monocarboxylate transporters to this adaptation of neuronal activity to repeated glucose deprivation was examined in LSN neurons. α‐Cyano‐4‐hydroxycinnamate (4‐CIN, 100 μM), an inhibitor of the monocarboxylate transporters, did not significantly affect the depression of the neuronal activity induced by the first glucose deprivation. However, in the presence of 4‐CIN (100 μM), a second glucose deprivation produced a typical depression of the neuronal activity, indicating that 4‐CIN had nullified the adaptation of neuronal activity to a second glucose deprivation. Cytochalasin B (CCB, 20 μM), an inhibitor of glucose transporters, depressed the neuronal activity in the presence of 11 mM glucose. Pyruvate (11 mM) partially restored the neuronal activity depressed by pretreatment with CCB (20 μM) for 30–40 min. These results suggest that antecedent glucose deprivation stimulates monocarboxylate‐transporters to supply energy substrates to LSN neurons, thus protecting the neurons against subsequent glucose deprivation. Synapse 49:97–105, 2003. © 2003 Wiley‐Liss, Inc.
Changes in NPY‐mediated modulation of hippocampal [3H]D‐aspartate outflow in the kindling model of epilepsy
Authors: Rodi Donata , Mazzuferi Manuela , Bregola Gianni , Dumont Yvan , Fournier Alain , Quirion Remi , Simonato Michele 
Published: May 2003

AbstractThe anticonvulsant effect of NPY may depend on Y2 and/or Y5 receptor‐mediated inhibition of glutamate release in critical areas, such as the hippocampus. However, Y2 and Y5 receptor levels have been reported to increase and decrease, respectively, in the epileptic hippocampus, implicating that the profile of NPY effects may change accordingly. The aim of this study was to evaluate the differential effects of NPY on glutamate release in the normal and in the epileptic hippocampus. Thus, we pharmacologically characterized the effects of NPY on the release of [3H]D‐aspartate, a valid marker of endogenous glutamate, from synaptosomes prepared from the whole hippocampus and from the three hippocampal subregions (dentate gyrus and CA1 and CA3 subfields) of control and kindled rats, killed 1 week after the last stimulus‐evoked seizure. In the whole hippocampus, NPY does not significantly affect stimulus‐evoked [3H]D‐aspartate overflow. In synaptosomes prepared from control rats, NPY significantly inhibited 15 mM K+‐evoked [3H]D‐aspartate overflow only in the CA1 subfield (approx. −30%). Both Y2 and Y5 receptor antagonists (respectively, 1 μM BIIE0246 and 1 μM CGP71683A) prevented this effect, suggesting the involvement of both receptor types. In contrast, in synaptosomes prepared from kindled rats NPY significantly inhibited 15 mM K+‐evoked [3H]D‐aspartate overflow in the CA1 subfield and in the dentate gyrus (approx. –30%). Only the Y2 (not the Y5) antagonist prevented these effects. These data indicate a critical role for the Y2 receptor in the inhibitory control of glutamate release in the kindled hippocampus and, thus, suggest that the anticonvulsant effect of NPY in the epileptic brain is most likely Y2, but not Y5, receptor‐mediated. Synapse 49:116–124, 2003. © 2003 Wiley‐Liss, Inc.