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Chemical Compounds (chemical + compound)

Distribution by Scientific Domains

Chemistry	45%
Life Sciences	22%
Medical Sciences	21%
Earth and Environmental Science	7%
2 Other Domains	5%

Distribution within Chemistry

Mass Spectrometry	33%
General & Introductory Food Science & Technology	22%
Analytical Chemistry	6%
9 Other Subdomains	39%

Kinds of Chemical Compounds

different chemical compound

Selected Abstracts

SENSORY CHARACTERISTICS OF CHEMICAL COMPOUNDS POTENTIALLY ASSOCIATED WITH BEANY AROMA IN FOODS,

JOURNAL OF SENSORY STUDIES, Issue 1 2004
SUNTAREE VARA-UBOL
ABSTRACT The sensory characteristic "beany" is a limiting factor in introducing soy products to many consumers in western cultures. This research described sensory properties of beany flavor and described sensory odor characteristics of 19 chemicals that have been associated with beany aroma and flavor in previous literature. Seven concentrations varying from 1 to 100,000 ppm of each chemical (if soluble in propylene glycol) were examined by a five member trained descriptive panel. The panel described beany as having multiple attributes. Musty/earthy, musty/dusty, sour aromatics, and characterizing attributes such as green/pea pod, nutty, or brown collectively imparted beany aroma and flavor of most beans. Starchy flavor and powdery texture also were intrinsically associated with beany in bean product samples. Some chemicals tested were not beany at any level tested. Three alcohols, two ketones, one aldehyde, and one pyrazine exhibited beany characteristics (green/peapod or brown) only at low concentrations, generally 1-10 ppm. [source]

2,2,-Nitrophenylisatogen potentiates P2X1 receptor mediated vascular contraction and blood pressure elevation

DRUG DEVELOPMENT RESEARCH, Issue 1 2003
Anna-Karin Wihlborg
Abstract The objective of this research was to examine the effects of chemical compounds with possible P2 receptor modulating effects and to characterize the potentiating effects of 2,2,-nitrophenylisatogen (NPI) on P2X1 receptors in vitro and in vivo. Chemical compounds were tested in an in vitro pharmacological assay using vascular segments from the rat mesenteric artery stimulated by P2 receptor-specific agonists. Contractions were expressed as a percentage of 60 mM K+ -induced contractions. Blood pressure was evaluated in pithed rats. NPI (30 ,M) added 15 min before addition of the P2X1 receptor-specific agonist ,,-MeATP increased the maximum vasoconstriction from 23% to 49% (an increase of 113%). Furthermore, NPI prevented the desensitization of repeated ,,-MeATP contractions. Related compounds were examined, and 2-(3-methoxy-phenyl)-1-oxy-indol-3-one (MPI) had similar effects as NPI, but several others lacked effect. NPI had no effect on ADP,S (P2Y1) or acetylcholine-mediated vasodilatation, nor on UTP (P2Y2/4), UDP (P2Y6), or noradrenaline-mediated contractions. In pithed rats, the blood pressure response to 50 nmol/kg-infusion of ,,-MeATP was increased from 50±6 to 63±5 mmHg (P<0.05), but had no effect on basal blood pressure or on the cardiovascular response to preganglionic nerve stimulation. In conclusion, NPI and MPI potentiates P2X1 receptor vascular contractions in vitro and (NPI) blood pressure effects in vivo. It is possible that the effect is mediated by an inhibition of P2X1 receptor desensitization. Drug Dev. Res. 59:82,87, 2003. © 2003 Wiley-Liss, Inc. [source]

Physical and chemical cues influencing the oviposition behaviour of Aphidius ervi

ENTOMOLOGIA EXPERIMENTALIS ET APPLICATA, Issue 3 2000
Donatella Battaglia
Abstract The oviposition behaviour of the aphid parasitoid Aphidius ervi Haliday is influenced by both chemical and physical cues. Oviposition attack responses were elicited by paint pigments sealed into the tip of a glass capillary tube. Parasitoids reacted to yellow pigments with repeated oviposition attack responses, but they did not react to green pigments. The spectrum of reflected light from the yellow pigments was very similar to that from the ,green' natural host Acyrthosiphon pisum (Harris), with a high proportion of the total radiation energy being emitted in the yellow-orange wavebands (580,660 nm). Pea aphid cornicle secretion also elicited oviposition attack responses, which were not exclusively induced by its pale yellow-green colour. In fact, the oviposition attack response to capillary tips coated with cornicle secretion remained evident under red light conditions, which, in contrast, nearly completely suppressed the response to yellow pigments. Chemical compounds from cornicle secretion do not appear to be involved in parasitoid orientation, even though they stimulate intense oviposition attack responses. Olfactometer experiments showed that the putative kairomone involved acts only at very short range or on contact. Host exuviae, which also elicited strong and persistent oviposition reactions from A. ervi females, appear to be a good alternative source of ovipositional kairomone(s). This work confirms the existence of an aphid cuticular kairomone. [source]

FS09.2 Contact allergy to a commercial alcohol prep swab

CONTACT DERMATITIS, Issue 3 2004
James S Taylor
Allergic contact dermatitis to prepackaged disposable alcohol prep swabs is infrequently reported. A 60-year-old woman developed repeated episodes of dermatitis at sites of injections and venipunctures. History and patch testing revealed contact allergy to Kendall Webcol alchol prep swabs. There were negative patch test results to isopropyl alcohol (IPA), but positive reactions to the Webcol swab, to the inner surface of the packaging foil, to two other brands of alcohol swabs, and to bacitracin. UV absorbance profile analysis revealed the presence of UV absorbing materials at peaks of 221 and 280 nm within commercial IPA samples, including one from Kendall, which were absent from reagent grade IPA. Reports of similar cases identified IPA, propylene oxide, or both as the allergens; when swab ingredients were negative, compound allergy was proposed. A recent report from Korea identified dodecyldiaminoethylglycine and IPA as the allergens in the commercial disinfectant swab. Although the exact allergen is undetermined in our case, it may represent a chemical compound or contaminant that is used or acquired during the manufacturing of the swabs or foils. [source]

Retinoic acid signaling is required for proper morphogenesis of mammary gland

DEVELOPMENTAL DYNAMICS, Issue 4 2005
Y. Alan Wang
Abstract Retinoic acid (RA), a bioactive chemical compound synthesized from dietary derived vitamin A, has been successfully used as a chemopreventive and chemotherapeutic agent through the regulation of cell proliferation, differentiation, and apoptosis acting via the retinoic acid receptors. Despite two decades of research on the function of retinoic acid, the physiological role of RA in mammary gland development is still not well characterized. In this report, we demonstrate that RA is required for proper morphogenesis of mouse mammary gland in a novel transgenic mouse model system. It was found that inhibition of RA signaling in vivo leads to excessive mammary ductal morphogenesis through upregulation of cyclin D1 and MMP-3 expression. Furthermore, we show that the transgene-induced excessive branching morphogenesis could be reversed by treatment with RA, demonstrating the direct physiological effect of RA signaling in vivo. In addition, we demonstrate that excessive branching morphogenesis in the transgenic mammary gland are cell-autonomous and do not require stromal signals within the transgenic mammary gland. Finally, we provide evidence suggesting that retinoic acid signaling is required for appropriate mammary gland differentiation. Collectively, our data indicate for the first time that retinoic acid signaling is required to maintain the homeostasis of mammary gland morphogenesis. Developmental Dynamics 234:892,899, 2005. © 2005 Wiley-Liss, Inc. [source]

Phage display as a novel screening tool for primary toxicological targets

ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 2 2010
Bieke Van Dorst
Abstract In the present study the use of phage display as a screening tool to determine primary toxicological targets was investigated. These primary toxicological targets are the targets in the cell with which a chemical compound initially interacts and that are responsible for consecutive (toxic) effects. Nickel was used as model compound for the present study. By selection of Ni-binding peptides out of a 12-mer peptide phage library, it was possible to identify primary toxicological targets of Ni (and other metals). The selected Ni-binding peptides showed similarities to important primary toxicological targets of Ni, such as the hydrogenase nickel incorporation protein (hypB) and the Mg/Ni/Co transporter (corA). This shows that phage display, which is already widely used in other research fields, also has potential in ecotoxicology, as a novel screening tool with which to determine primary toxicological targets of chemical compounds. Environ. Toxicol. Chem. 2010;29:250,255. © 2009 SETAC [source]

MassBank: a public repository for sharing mass spectral data for life sciences

JOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 7 2010
Hisayuki Horai
Abstract MassBank is the first public repository of mass spectra of small chemical compounds for life sciences (<3000 Da). The database contains 605 electron-ionization mass spectrometry(EI-MS), 137 fast atom bombardment MS and 9276 electrospray ionization (ESI)-MSn data of 2337 authentic compounds of metabolites, 11 545 EI-MS and 834 other-MS data of 10 286 volatile natural and synthetic compounds, and 3045 ESI-MS2 data of 679 synthetic drugs contributed by 16 research groups (January 2010). ESI-MS2 data were analyzed under nonstandardized, independent experimental conditions. MassBank is a distributed database. Each research group provides data from its own MassBank data servers distributed on the Internet. MassBank users can access either all of the MassBank data or a subset of the data by specifying one or more experimental conditions. In a spectral search to retrieve mass spectra similar to a query mass spectrum, the similarity score is calculated by a weighted cosine correlation in which weighting exponents on peak intensity and the mass-to-charge ratio are optimized to the ESI-MS2 data. MassBank also provides a merged spectrum for each compound prepared by merging the analyzed ESI-MS2 data on an identical compound under different collision-induced dissociation conditions. Data merging has significantly improved the precision of the identification of a chemical compound by 21,23% at a similarity score of 0.6. Thus, MassBank is useful for the identification of chemical compounds and the publication of experimental data. Copyright © 2010 John Wiley & Sons, Ltd. [source]

Testing Marginal Homogeneity Against Stochastic Order in Multivariate Ordinal Data

BIOMETRICS, Issue 2 2009
B. Klingenberg
Summary Many assessment instruments used in the evaluation of toxicity, safety, pain, or disease progression consider multiple ordinal endpoints to fully capture the presence and severity of treatment effects. Contingency tables underlying these correlated responses are often sparse and imbalanced, rendering asymptotic results unreliable or model fitting prohibitively complex without overly simplistic assumptions on the marginal and joint distribution. Instead of a modeling approach, we look at stochastic order and marginal inhomogeneity as an expression or manifestation of a treatment effect under much weaker assumptions. Often, endpoints are grouped together into physiological domains or by the body function they describe. We derive tests based on these subgroups, which might supplement or replace the individual endpoint analysis because they are more powerful. The permutation or bootstrap distribution is used throughout to obtain global, subgroup, and individual significance levels as they naturally incorporate the correlation among endpoints. We provide a theorem that establishes a connection between marginal homogeneity and the stronger exchangeability assumption under the permutation approach. Multiplicity adjustments for the individual endpoints are obtained via stepdown procedures, while subgroup significance levels are adjusted via the full closed testing procedure. The proposed methodology is illustrated using a collection of 25 correlated ordinal endpoints, grouped into six domains, to evaluate toxicity of a chemical compound. [source]

A patch test study of 27 crude drugs commonly used in Chinese topical medicaments

CONTACT DERMATITIS, Issue 1 2003
Hsuan-Hsiang Chen
Chinese topical medicaments (CTMs) are commonly used in Taiwan and in Southeast Asia. However, a systematic evaluation of contact sensitization potential from CTM has not been carried out to our knowledge. This study was undertaken to investigate the incidence of contact sensitivity to the components of CTM in patients with contact dermatitis from CTM. A screening series of 27 crude drugs most commonly used in CTM as well as a modified European standard series was patch tested in 30 patients. The herbs with the most frequent positive reactions were Flos Caryophylli ( ), Radix Angelicae Pubescentis ( ), Cortex Cinnamomi ( ), Cortex Radix Acanthopanacis ( ), Caulis Impatientis ( ), Resina Draconis/Sanguis Draconis ( ), Fructus Cnidii ( ), Radix Gentiana Macrophyllae ( ), and Rhizoma Ligustici Chuanxiong ( ). Concomitant allergy to colophonium was found in most of these positive reactions. Reducing the concentration and simplifying the compositions of these components, as well as replacement with those of low allergenicity in CTM, such as Rhizoma Arisaematis ( ), Herba Lycopodii ( ), Radix Cyathulae Officinalis ( ), Rhizoma Pinelliae ( ), Radix Angelicae Dahuricae ( ), Herba Dendrobii ( ), Secretio Moschus ( ), and Stigmata Croci ( ), may be advocated. A precise labelling of the dosage of each component and the exact chemical compounds in CTM products could further improve the safety and therapeutic effects of CTM in the future. [source]

2,2,-Nitrophenylisatogen potentiates P2X1 receptor mediated vascular contraction and blood pressure elevation

Morphology and chemical composition of metathoracic scent glands in Dolycoris baccarum (Linnaeus, 1758) (Heteroptera: Pentatomidae)

ACTA ZOOLOGICA, Issue 3 2008
Dilek Durak
Abstract One of the general defining characters of the Heteroptera is the presence of metathoracic scent glands (MTG). Using scanning electron microscopy, the morphology of the MTG of Dolycoris baccarum (Linnaeus 1758) (Heteroptera: Pentatomidae) was studied. The MTG belong to the diastomian type. The two glandular pores located between the mesothoracic and metathoracic coxae are associated with ,mushroom-like' structures. The MTG are composed of a reservoir and a pair of lateral glands is connected to the reservoir by a duct. A groove-like structure extends downwards from the ostiole. While this structure is long and wide, its ostiole is oval. Extracts of the volatile fractions from male and female MTG secretions were analysed by capillary gas chromatography,mass spectrometry (GC-MS) and exhibited a typical pentatomid composition. Seventeen chemical compounds were detected in female secretions, whereas 13 chemical compounds were detected in the male secretions. Most chemical compounds were similar between the sexes but were different in their quantities. In this regard, the compounds identified were investigated and the biological functions of the glandular secretions were discussed. In the analyses of the MTG of females of D. baccarum, tridecane (50.97%) was a major odour component and (Z,Z)-4,16-octadecadien-1-ol acetate (0.02%) was a minor odour component. In males, tridecane (50.80%) was a major odour component and 1,2-benzenedicarboxylic acid (0.02%) was a minor odour component. [source]

Fate of Pesticides in the Environment and its Bioremediation

ENGINEERING IN LIFE SCIENCES (ELECTRONIC), Issue 6 2005
M. Gavrilescu
Abstract The present paper is an overview of the presence and fate of pesticides as persistent organic pollutants in the environment as well as of the potential for their detoxification, also combined with chemical and physical treatment. It contains information gathered from a range of currently available sources. The fate of pesticides in the environment is analyzed considering the processes that determine their persistence and mobility, grouped into transport, transfer and transformation processes. Few pesticide characteristics such as persistence, mobility and biodegradability are emphasized. The fate of a pesticide and the potential for its persistence and mobility from the site of application are considered to be affected by the chemical and physical properties of the pesticide, site characteristics such as soil and groundwater individuality, climate and local weather conditions, biological population, and the handling practices of the pesticide user. Bioremediation, as one of the most environmentally-sound and cost-effective methods for the decontamination and detoxification of a pesticide-contaminated environment is discussed especially considering the factors affecting the biodegradability of pesticides such as biological factors and the characteristics of the chemical compounds. In situ and ex situ bioremediation as possible types of bioremediation activities are weighted up. Also, the paper includes some considerations for developing strategies regarding the choice of bioremediation technology, as well as advantages and disadvantages of the bioremediation of environmental components polluted with pesticides. [source]

Difference in the sensitivity to chemical compounds between female and male neonates of Daphnia magna

ENVIRONMENTAL TOXICOLOGY, Issue 5 2008
Erika Ikuno
Abstract Daphnia magna usually produce female offspring by parthenogenesis, and thus only female neonates are used to evaluate the environmental toxicity to chemicals. Additionally, it is known that male daphnids are induced by exposure to a juvenile hormone, methyl farnesoate, during late ovarian development. In this study, we investigated the concentration of methyl farnesoate in a 24-h exposure producing 100% males, and the difference in sensitivity to chemical compounds, potassium dichromate, pentachlorophenol, and paraquat, between females and males, referring to OECD Test Guideline 202. The results show that the minimum concentration for 100%-male induction of methyl farnesoate in adult females was 50 ,g/L. In addition, acute toxicity tests (immobility test) with the other chemicals showed that male neonates have higher tolerance to potassium dichromate and pentachlorophenol than females for at least 24 h after birth, while no sex difference was observed in the sensitivity to paraquat. The differences in the median effective concentrations in these compounds between female and male neonates suggest two different overall modes of action. Using female daphnids for environmentally toxicity testing seems reasonable, since the females are more sensitive to chemicals than males. Furthermore, the method of male induction established in this study could be used for screening of endocrine disruptors. © 2008 Wiley Periodicals, Inc. Environ Toxicol, 2008. [source]

Cytotoxicity and oxidative stress caused by chemicals adsorbed on particulate matter,

ENVIRONMENTAL TOXICOLOGY, Issue 5 2006
Andrea Müller
Abstract Air particulate matter (PM) and bound chemicals are potential mediators for adverse health effects. The cytotoxicity and changes in energy-providing processes caused by chemical compounds bound to PM of different size fractions were investigated in Tetrahymena pyriformis. The PM samplings were carried out using a high volume cascade impactor (6 size fractions between 10 ,m and less than 0.49 ,m) at three points of La Plata, Argentina: in an industrial area, a traffic-influenced urban area, and a control area. Extracts from respirable particles below 1 ,m initiated the highest cytotoxic effects, demonstrating their higher risk. In contrast, an increase on oxygen consumption was observed especially in tests of extracts from particles less than 1 ,m from urban and industrial areas. The increase on oxygen consumption could be caused by decoupling processes in the respiratory chain. Otherwise the ATP concentration was increased too, even though to a lower extent. The observed imbalance between oxygen consumption and ATP concentration in exposed T. pyriformis cells may be due to oxidative stress, caused by chemical compounds bound to the particles. Owing to the complexity of effects related to PM and their associated chemical compounds, various physiological parameters necessarily need to be investigated to obtain more information about their possible involvement in human relevant pathogenic processes. As shown here, effects on cell proliferation and on energy-providing processes are suitable indicators for the different impact of PM and adsorbed chemicals from various sampling locations. © 2006 Wiley Periodicals, Inc. Environ Toxicol 21: 457,463, 2006. [source]

Phage display as a novel screening tool for primary toxicological targets

The role of biomarkers to assess oil-contaminated sediment quality using toxicity tests with clams and crabs,

ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 6 2008
Carmen Morales-Caselles
Abstract A 28-d bioassay was conducted with two invertebrate species with different feeding habits, the clam Ruditapes philippinarum and the shore crab Carcinus maenas. The purpose of the present study was to assess the quality of sediments affected by oil spills in different areas of the Spanish coast. The organisms were exposed to environmental samples of oil-contaminated sediments during four weeks and, after the experiment, a suite of biomarkers of exposure was measured: The phase one detoxification system was assessed by ethoxyresorufin- O -deethylase (EROD) activity; glutathione- S -transferase (GST) is a phase-two detoxification enzyme but also is implicated in oxidative stress events; glutathione peroxidase (GPX), glutathione reductase (GR), and the ferric reducing ability of plasma (FRAP) assay were analyzed to determine the antioxidant activity of the tissues. The biomarker results were correlated with the chemical compounds bound to sediments (polycyclic aromatic hydrocarbons [PAHs], polychlorinated biphenyls [PCBs], Zn, Cd, Pb, Cu, Ni, Co, V) and a principal component analysis was carried out with the purpose of linking all the variables and to detect those contaminated sediments potentially harmful to the biota. Results showed induction of biomarkers in both invertebrate species and significant differences (p < 0.05; p < 0.01) were established among sediments affected by different spills. The use of the selected biomarkers together with the sediment chemical analysis assesses the bioavailability of contaminants and has proven to be a suitable tool to monitor the environmental quality of sediments affected by oil spills. [source]

Temporal and shrub adaptation effect on soil microbial functional diversity in a desert system

EUROPEAN JOURNAL OF SOIL SCIENCE, Issue 6 2009
V. Saul-Tcherkas
Summary The Negev Desert is characterized by spatial and temporal patterns of resource distribution, in which soil biota are considered to be among the most sensitive biological characteristics, easily influenced by changes related to soil and abiotic factors. Soil water availability and organic matter are among the most important factors, acting as triggers that determine the length of the period of activity. The main source of organic matter in this xeric environment is input from annual and perennial shrubs. In order to persist and propagate in this xeric environment, the plants have developed different ecophysiological adaptations (e.g. the excretion of salt (Reaumuria negevensis) and chemical compounds (Artemisia sieberi) via the leaves). We found that the values of soil moisture obtained for soil samples collected in the vicinity of R. negevensis were larger than for samples collected in the vicinity of Noaea mucronata and A. sieberi and in the open area. The maximum values of CO2 evolution, microbial biomass and Shannon index (H,) were obtained for the samples collected from the vicinity of N. mucronata. Therefore, we assume that the vicinity of N. mucronata afforded the best conditions for the soil bacterial community. In the Negev Desert, we also found that water availability and pulses of rain compared with frequent rainfall influenced CO2 evolution, microbial biomass, qCO2 and the Shannon index (H,). The differences in water amount and availability between the two rainy seasons caused larger values in most of the properties during the first four seasons (December 2005,November 2006) compared with the last four seasons (December 2006,November 2007) for most of the samples. [source]

Prediction of missing enzyme genes in a bacterial metabolic network

FEBS JOURNAL, Issue 9 2007
Reconstruction of the lysine-degradation pathway of Pseudomonas aeruginosa
The metabolic network is an important biological network which consists of enzymes and chemical compounds. However, a large number of metabolic pathways remains unknown, and most organism-specific metabolic pathways contain many missing enzymes. We present a novel method to identify the genes coding for missing enzymes using available genomic and chemical information from bacterial genomes. The proposed method consists of two steps: (a) estimation of the functional association between the genes with respect to chromosomal proximity and evolutionary association, using supervised network inference; and (b) selection of gene candidates for missing enzymes based on the original candidate score and the chemical reaction information encoded in the EC number. We applied the proposed methods to infer the metabolic network for the bacteria Pseudomonas aeruginosa from two genomic datasets: gene position and phylogenetic profiles. Next, we predicted several missing enzyme genes to reconstruct the lysine-degradation pathway in P. aeruginosa using EC number information. As a result, we identified PA0266 as a putative 5-aminovalerate aminotransferase (EC 2.6.1.48) and PA0265 as a putative glutarate semialdehyde dehydrogenase (EC 1.2.1.20). To verify our prediction, we conducted biochemical assays and examined the activity of the products of the predicted genes, PA0265 and PA0266, in a coupled reaction. We observed that the predicted gene products catalyzed the expected reactions; no activity was seen when both gene products were omitted from the reaction. [source]

Effect of different chemical compounds as coadjutants of 4-hexylresorcinol on the appearance of deepwater pink shrimp (Parapenaeus longirostris) during chilled storage

INTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 11 2008
Oscar Martínez-Alvarez
Summary Different chemical compounds (kojic acid, cumic acid, phytic acid, sodium metabisulphite, magnesium carbonate, sorbic acid and different protease inhibitors) were used as coadjutants in 4-hexylresorcinol (4-HR)-based melanosis-inhibiting formulas tested for inhibiting melanosis in pink shrimp (Parapenaeus longirostris). The experiment was performed on board ship. Increasing concentrations of 4-HR delayed the occurrence of melanosis during storage. However, 4-HR could not prevent the appearance of a yellow-greenish colouration in the cephalothorax that diminishes the consumer acceptability of shrimps. The incorporation of protease inhibitors (ethylenediaminetetraacetic acid, disodium dihydrogen pyrophosphate, iodoacetic acid, egg white and phenylmethylsulphonyl fluoride) into the 4-HR-based mixtures improved the acceptability after storage, suggesting that protease activity post-mortem contributes to the reduction in the final acceptability of crustaceans. [source]

Neural network modeling of physical properties of chemical compounds

INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 1 2001
J. Kozio
Abstract Three different models relating structural descriptors to normal boiling points, melting points, and refractive indexes of organic compounds have been developed using artificial neural networks. A newly elaborated set of molecular descriptors was evaluated to determine their utility in quantitative structure,property relationship (QSPR) studies. Applying two data sets containing 190 amines and 393 amides, neural networks were trained to predict physical properties with close to experimental accuracy, using the conjugated gradient algorithm. Obtained results have shown a high predictive ability of learned neural networks models. The fit error for the predicted properties values compared to experimental data is relatively small. © 2001 John Wiley & Sons, Inc. Int J Quant Chem 84: 117,126, 2001 [source]

Biomarkers as biological indicators of xenobiotic exposure

JOURNAL OF APPLIED TOXICOLOGY, Issue 4 2001
Fernando Gil
Abstract The presence of a xenobiotic in the environment always represents a risk for living organisms. However, to talk about impregnation there is a need to detect toxicity in the organism, and the concept of intoxication is related to specific organ alterations and clinical symptoms. Moreover, the relationship between the toxic levels within the organism and the toxic response is rather complex and has a difficult forecast because it depends on several factors, namely toxicokinetic and genetic factors. One of the methods to quantify the interaction with xenobiotics and its potential impact on living organisms, including the human being, is monitoring by the use of the so-called biomarkers. They can provide measures of the exposure, toxic effect and individual susceptibility to environmental chemical compounds and may be very useful to assess and control the risk of long-term outcomes associated with exposure to xenobiotic (i.e. heavy metals, halogenated hydrocarbons, pesticides). Copyright © 2001 John Wiley & Sons, Ltd. [source]

Determination of atomic valence indices from population analyses at correlated level

JOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 15 2003
R. Bochicchio
Abstract This work carries out a study of atomic valences within molecular systems based on Mulliken and topological population analyses at correlated level. The use of the unpaired electron densities leads to suitable relationships between valences, free valence indices, and bond indices, which turn out to be quite useful for computational purposes. The results arising from both methods at correlated and uncorrelated levels are compared in a large series of chemical compounds. Several interesting conclusions are drawn out and analyzed in detail. © 2003 Wiley Periodicals, Inc. J Comput Chem 24: 1902,1909, 2003 [source]

Protecting the Nation's Critical Infrastructure: The Vulnerability of U.S. Water Supply Systems

JOURNAL OF CONTINGENCIES AND CRISIS MANAGEMENT, Issue 2 2000
Robert M. Clark
Terrorism in the United States was not considered a serious threat until the second half of the 1990s. However, recent attacks both at home and abroad have forced government planners to consider the possibility that critical elements of the U.S. infrastructure might in fact be vulnerable to terrorism. The potential for chemical or biological contamination of water supply systems exists along with the possibility that such systems might be sabotaged. This article reviews the threat of biological and chemical compounds in relation to the characteristics of water supply systems. Vulnerability of such systems to terrorist attacks is examined, as well as possible physical and chemical countermeasures that could be applied. A case study is presented of an accidental contamination event that illustrates the difficulty of tracking such events in a drinking water system. It can be concluded that municipal water supplies are vulnerable. However, appropriate physical planning of such systems, including contingency back-up with separate water lines for emergencies, coupled with proactive monitoring, will significantly increase security in the face of possible terrorist attacks. [source]

Local adaptation to biotic factors: reciprocal transplants of four species associated with aromatic Thymus pulegioides and T. serpyllum

JOURNAL OF ECOLOGY, Issue 5 2008
Eva Grøndahl
Summary 1A plant producing secondary compounds may affect the fitness of other plants in the vicinity, and, likewise, associated plants may evolve adaptation to the presence of their ,chemical neighbour'. Species of the genus Thymus are aromatic plants, well known for their production of aromatic oils whose constitution is dominated by mono- or sesquiterpenes. A polymorphism for the production of the dominant terpene in the oil exists both within and between thyme species. 2Here we examine the effects of two different terpenes produced by Thymus pulegioides and T. serpyllum on the performance of four associated plant species: Achillea millefolium, Agrostis capillaris, Galium verum and Plantago lanceolata. In a reciprocal transplant experiment we studied how plants naturally occurring together with thyme producing either carvacrol or b-caryophyllene perform on soil treated with these compounds. 3We found evidence of local adaptation to the ,home' terpene. Plants originating from sites where they grow together with carvacrol-producing thyme plants also perform better on soil treated with carvacrol. One of the associated species (A. millefolium) also showed evidence of local adaptation to the sesquiterpene b-caryophyllene . 4Seed germination and root biomass showed an adaptive response to soil treatment. Vegetation analysis supported the results of the reciprocal transplant experiment. When the associated species performed best on ,home' soil, thyme and the associated species also showed a positive spatial association at natural sites of origin. Moreover, coefficients of variation in plant traits were significantly lower on ,home' soil compared to other soils for both A. capillaris and A. millefolium, but higher for G. verum. 5Synthesis. Our results show that plant species can adapt to the presence of neighbour plants that produce specific chemical compounds. This supports the idea that local plant communities may be a lot more co-evolved than was previously thought. [source]

ANTIBACTERIAL ACTIVITY AND CHEMICAL CONSTITUTIONS OF OLEA EUROPAEA L. LEAF EXTRACTS

JOURNAL OF FOOD PROCESSING AND PRESERVATION, Issue 3 2010
MIHRIBAN KORUKLUOGLU
ABSTRACT The in vitro antimicrobial activity of aqueous, acetone, diethyl ether and ethyl alcohol extracts of olive leaves (Olea europaea L.) was studied. The aqueous extract of olive leaves had no antibacterial effect against the test microorganisms, whereas acetone extract showed inhibitory effect on Salmonella enteritidis, Bacillus cereus, Klebsiella pneumoniae, Escherichia coli, Enterococcus faecalis, Streptococcus thermophilus and Lactobacillus bulgaricus. Furthermore, the antimicrobial activities of some phenolic compounds against microorganisms were tested. The most effective compound was found to be oleuropein while syringic acid was found ineffective. The characterization of phenolic compounds in different extracts determined by high performance liquid chromatography-air pressure chemical ionization-mass spectrometry detector (HPLC-APCI-MSD GC-MS) gas chromatography-mass spectrometry (GC-MS). The acetone and the ethyl alcohol extracts had the most and the least oleuropein content, respectively. PRACTICAL APPLICATIONS In recent years the extracts of many plant species have become popular, and attempts to characterize their bioactive principles have gained speed for many pharmaceutical and food-processing applications. Especially, antimicrobial properties of plants have revived as a consequence of current problems associated with the use of chemical preservatives. Because of consumers' negative perspectives of synthetic preservatives, attention is shifting toward natural alternatives. The findings suggest that olive leaf extracts and their phenolic compounds have good potential as antibacterial substances in food preservation as they may be more acceptable to consumers and the regulatory agencies in comparison with synthetic chemical compounds. [source]

EFFECTS OF ORGANIC ACIDS, NISIN, LYZOZYME AND EDTA ON THE SURVIVAL OF YERSINIA ENTEROCOLITICA POPULATION IN INOCULATED ORANGE BEVERAGES

JOURNAL OF FOOD SAFETY, Issue 1 2010
CECILIA S.M. LUCERO ESTRADA
ABSTRACT Inactivation of a Yersinia enterocolitica strain by 3.4% ascorbic acid (AA), 0.5% citric acid (CA), 0.2% lactic acid, 100 IU/mL nisin, 2,400 IU/mL lysozyme and 20 mM ethylenediaminetetraacetic acid disodium salt (EDTA ), alone and combined, was studied at different temperatures (4 and 25C) in commercial and laboratory-prepared orange beverages. In laboratory-prepared juice, highest reductions (between 3.06 and 4.07 log units) were obtained with acid mixtures at 25C after 20 min of incubation. At 24 h of incubation, EDTA was bactericidal and the mixtures with nisin or lysozyme resulted in count reductions of 6.03 and 5.98 log units, respectively. In commercial orange beverage, AA and CA gave reductions of 5.43 and 4.26 log units, respectively. The three acid mixtures were bactericidal within the first 10 min. EDTA alone or mixed completely inhibited Y. enterocolitica strain at 6 and 24 h of incubation. At 4C, all the results were significantly lower than at 25C. PRACTICAL APPLICATIONS Yersinia enterocolitica is a common cause of gastrointestinal disorders and may lead to sequelae. This pathogen can maintain its virulence in a wide temperature range and under adverse conditions such as pH lower than 4. There are reports describing the isolation of Y. enterocolitica from water and ice in Brazil and Latin America. The sale of unpasteurized drinks is a common practice in our region and their consumption has increased over the past years. In the present work, chemical compounds and biological inhibitors were studied. Some of these compounds showed to be efficient for reducing Y. enterocolitica populations. Furthermore, they did not modify the organoleptic characteristics of the beverages and they are not toxic for human beings. [source]

Characterization of Aroma-Active Compounds in Microwave Blanched Peanuts

JOURNAL OF FOOD SCIENCE, Issue 9 2006
A.V. Schirack
ABSTRACT:, Microwave blanching of peanuts has been explored as an alternative to conventional oven methods based on its speed of operation, energy savings, and efficiency of process control. Although processing times can be greatly reduced, the occurrence of stale/floral and ashy off-flavors has been reported at high process temperatures. This study examined the chemical compounds responsible for this off-flavor using solvent extraction/solvent assisted flavor evaporation (SAFE), gas chromatography-olfactometry (GC/O), gas chromatography-mass spectrometry (GC/MS), and aroma extract dilution analysis (AEDA). Select compounds were quantified based on AEDA results using SAFE and GC/MS. Quantification, threshold testing, and analysis of model systems revealed increased formation of guaiacol and phenylacetaldehyde in the off-flavored peanuts, which resulted in the burnt and stale/floral flavors noted by a trained panel. [source]

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Multi-component analysis: blind extraction of pure components mass spectra using sparse component analysis

JOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 9 2009
Ivica Kopriva
Abstract The paper presents sparse component analysis (SCA)-based blind decomposition of the mixtures of mass spectra into pure components, wherein the number of mixtures is less than number of pure components. Standard solutions of the related blind source separation (BSS) problem that are published in the open literature require the number of mixtures to be greater than or equal to the unknown number of pure components. Specifically, we have demonstrated experimentally the capability of the SCA to blindly extract five pure components mass spectra from two mixtures only. Two approaches to SCA are tested: the first one based on ,1 norm minimization implemented through linear programming and the second one implemented through multilayer hierarchical alternating least square nonnegative matrix factorization with sparseness constraints imposed on pure components spectra. In contrast to many existing blind decomposition methods no a priori information about the number of pure components is required. It is estimated from the mixtures using robust data clustering algorithm together with pure components concentration matrix. Proposed methodology can be implemented as a part of software packages used for the analysis of mass spectra and identification of chemical compounds. Copyright © 2009 John Wiley & Sons, Ltd. [source]

Diffusion of reduced arecoline and arecaidine through human vaginal and buccal mucosa

JOURNAL OF ORAL PATHOLOGY & MEDICINE, Issue 4 2001
P. Van der Bijl
Abstract: Because alkaloids from areca nut, arecoline and arecaidine, have been implicated in the development of oral submucous fibrosis, we determined their diffusion kinetics through human buccal and vaginal mucosa. Four clinically healthy vaginal mucosa specimens (mean patient age± standard deviation: 47±15 years; age range: 31,60 years) and 4 buccal mucosa specimens from 2 male patients and 2 female patients (mean patient age±standard deviation: 31±9 years; age range: 17,53 years) were obtained during surgery. In vitro flux rates of reduced arecoline and arecaidine (r-arecoline and r-arecaidine) were determined by use of a flow-through diffusion apparatus. Analysis of variance, a Duncan multiple range test, and an unpaired t -test were used to determine steady state kinetics and flux differences over time intervals. Although statistically significant differences were observed between flux values for both alkaloids and tissues at certain time points, these were not considered to be of biological (clinical) significance. However, the flux rates across both mucosa of r-arecoline were significantly higher statistically than those of r-arecaidine. The findings demonstrated the differences in the diffusion kinetics between r-arecoline and r-arecaidine across human buccal and vaginal mucosa, an observation that could be explained in terms of their ionisation characteristics. Additionally, the results obtained further support the hypothesis that human vaginal mucosa can be used as a model for buccal mucosa in studies of permeability to various chemical compounds. [source]