Joelle M R Gola

University College London, Londinium, England, United Kingdom

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Publications (13)32.32 Total impact

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    ABSTRACT: A simple method is reported for the estimation of in vivo air-tissue partition coefficients of VOCs and of in vitro blood-tissue partition coefficients for volatile organic compounds and other compounds. Linear free energy relationships for tissues such as brain, muscle, liver, lung, kidney, heart, skin and fat are available and once the Abraham descriptors are known for a compound, no more than simple arithmetic is required to estimate air-tissue and blood-tissue partitions.
    Chemosphere 07/2014; 120C:188-191. · 3.14 Impact Factor
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    ABSTRACT: There is considerable interest in blood-tissue distribution of agrochemicals and a number of workers have developed experimental methods for in vitro distribution. These methods involve the determination of saline-blood and saline-tissue partitions; not only are they indirect, but they do not yield the required in vivo distribution. We set out equations for gas-tissue and blood-tissue distribution, for partition from water into skin and for permeation from water through human skin. Together with Abraham descriptors for the agrochemicals, these equations can be used to predict values for all these processes. Our predictions compare favourably to experimental in vivo blood-tissue distribution where available. The predictions require no more than simple arithmetic. The present method represents a much easier and much more economic method of estimation of blood-tissue partitions than does the method that uses saline-blood and saline tissue partitions. It has the additional advantages that it yields the required in vivo partitions, and is easily extended to the prediction of partition of agrochemicals from water into skin, and permeation from water through skin.
    Pest Management Science 09/2013; · 2.74 Impact Factor
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    ABSTRACT: The 1:1 equilibrium constants, K, for the association of hydrogen bond bases and hydrogen bond acids have been determined by using octan-1-ol solvent at 298 K for 30 acid-base combinations. The values of K are much smaller than those found for aprotic, rather nonpolar solvents. It is shown that the log K values can satisfactorily be correlated against α(H)(2)·β(H)(2), where α(H)(2) and β(H)(2) are the 1:1 hydrogen bond acidities and basicities of solutes. The slope of the plot, 2.938, is much smaller than those for log K values in the nonpolar organic solvents previously studied. An analysis of literature data on 1:1 hydrogen bonding in water yields a negative slope for a plot of log K against α(H)(2)·β(H)(2), thus showing how the use of very strong hydrogen bond acids and bases does not lead to larger values of log K for 1:1 hydrogen bonding in water. It is suggested that for simple 1:1 association between monofunctional solutes in water, log K cannot be larger than about -0.1 log units. Descriptors have been obtained for the complex between 2,2,2-trifluoroethanol and propanone, and used to analyze solvent effects on the two reactants, the complex, and the complexation constant.
    The Journal of Organic Chemistry 10/2010; · 4.56 Impact Factor
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    ABSTRACT: Odour detection thresholds, that we have previously obtained, have been analysed by a general equation for selective transport. It is shown that such selective transport can account for some 77% of the total effect. The remainder is due to a specific size effect, that might involve odour-binding proteins, and a specific effect for aldehydes and carboxylic acids. Our analysis raises the question of whether selective transport is physically separable from the specific effects of receptor activation. The model predicts a chemical cut-off in odour detection along any homologous series.
    Chemical Senses 03/2002; 27(2):95-104. · 3.22 Impact Factor
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    ABSTRACT: We measured psychometric (i.e. concentration-response) functions for the detection of odor, nasal pungency and eye irritation from butyl acetate and toluene. Olfactory detection was measured in subjects with normal olfaction (i.e. normosmics) for whom nasal trigeminal detection does not interfere because it requires much higher concentrations. Nasal trigeminal detection, called nasal pungency, was measured only in subjects lacking olfaction (i.e. anosmics) in order to avoid odor interference. Ocular trigeminal detection, called eye irritation, was measured in both groups. The method employed entailed a two-alternative, forced-choice procedure with presentation of increasing concentrations. The outcome showed, for both chemicals, similar ocular trigeminal chemosensitivity in normosmics and anosmics and similar overall ocular and nasal trigeminal chemosensitivity. Olfactory sensitivity was much higher than both forms of trigeminal sensitivity by concentration differences of six and four orders of magnitude for butyl acetate and toluene, respectively. Detectability plots (i.e. detection performance vs log concentration) for the three sensory endpoints followed an S-shaped function with a middle range section that showed a robust linear fit (r > 0.94) on graphs of z-score vs log concentration. These detectability functions allow the calculation of olfactory and trigeminal thresholds at various levels of performance. At a point half-way between random and perfect detection, trigeminal and olfactory threshold concentrations were, respectively, 0.67 (+/-0.32) and 2.28 (+/-1.77) log units lower than those measured by us in the past for the same chemicals using an analogous procedure but under just one, fixed, level of performance. The available data suggest that, although considerably laborious, detectability functions provide chemosensory thresholds of closer relevance to environmentally realistic conditions (e.g. whole-body exposures).
    Journal of Applied Toxicology 01/2002; 22(1):25-30. · 2.60 Impact Factor
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    ABSTRACT: To probe into the rules of trigeminal chemosensory agonism in a binary mixture of chemicals we measured, first, the detectability (i.e., psychometric) function for eye irritation and for nasal pungency of butyl acetate and toluene, singly. (To avoid olfactory biases, nasal pungency was measured in a group of anosmics, i.e., persons lacking a functional sense of smell.) Then, based on the detectability function obtained for the individual chemicals, we prepared mixtures where the 2 components varied in their relative proportions but, if a simple rule of complete sensory agonism (in the sense of dose-additivity) were to hold, the mixtures should be as detectable as the reference concentration of each of the single chemicals. For both trigeminal endpoints (i.e., eye irritation and nasal pungency), the results showed that stimuli of relatively low detectability did show complete sensory agonism, whereas stimuli of relatively high detectability fell short of complete sensory agonism when compared with the detectability of the single substances. Further testing of additional binary and higher order mixtures will confirm whether or not a structure-activity model of trigeminal chemosensory impact of single chemicals, based on selected physicochemical parameters of the stimuli, can also be applied to chemical mixtures.
    Toxicological Sciences 11/2001; 63(2):233-44. · 4.33 Impact Factor
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    ABSTRACT: We have previously used two general solvation equations to correlate and to interpret a wide variety of physico-chemical and biochemical properties of compounds (solutes). Application of these equations requires a knowledge of the relevant solute descriptors, viz. R2, the excess molar refraction, π2H the solute dipolarity/polarizability, ∑α2H, ∑β2H the solute overall hydrogen bond acidity and basicity, and logL16, where L16 is the solute gas–hexadecane partition coefficient at 298K. We have also shown that these solute descriptors can be obtained from partition coefficients of solutes in various water–solvent and gas–solvent systems. Here, we use this approach to calculate solute descriptors for a series of 18 organofluorocarbons, classed as refrigerants, including chlorofluorocarbons, hydrochlorofluorocarbons, hydrofluorocarbons and perfluorocarbons, using Henry’s law coefficients in water and five organic solvents that we have already measured. These data have been used to calculate Ostwald solubility coefficients, logL. Gas–water and gas–solvent partitions have been then combined to give logP for partition between water and solvent. A number of logP and L values have also been taken from the Medchem97 database. There are enough data to obtain the above descriptors for the 18 organofluorocarbons, and then to estimate logP and L values in a large number of other solvents. The chemosensory properties of the organofluorocarbons are also estimated.
    Fluid Phase Equilibria 01/2001; 180(1):41-58. · 2.38 Impact Factor
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    ABSTRACT: A general equation set up for the study of transport properties has been applied to volatile organic compound (VOC) nasal pungency and eye irritation thresholds, as log (1/NPT) and log (1/EIT). The equation accounts for 93–95% of the total effect, thus suggesting that the main step is transport of the VOC from the gas phase to a receptor phase. In the case of odour thresholds the general equation accounts for only 77% of the total effect. A modified equation incorporates a factor for aliphatic aldehydes and carboxylic acids, and a general size effect that depends on the VOC maximum length. The size effect is important in that it leads to a cut-off effect that greatly reduces the potency of higher homologues. The various equations can all be used to predict chemosensory thresholds for thousands of VOCs.
    Indoor and Built Environment 01/2001; 10:252-257.
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    ABSTRACT: There are no previous references to the direct use of GLC data in the correlation of biological processes, but we show that GLC retention data can be used in the correlation of several such processes involving gaseous solutes. There are a number of reports of RP-HPLC and MEKC data being used in the correlation of biological processes, but they are mostly restricted as to the number and type of solute studied. We show that if chromatographic data are used to obtain solvation descriptors for solutes, and if these descriptors are then used in the correlation of biological processes, that this indirect connection is a much more powerful and generally applicable method than is the direct connection between chromatographic data and biological data.
    Journal of chromatography. B, Biomedical sciences and applications 09/2000; 745(1):103-15.
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    ABSTRACT: Using representative members of each of three homologous series of chemicals-ketones, acetates and alcohols-we measured nasal pungency thresholds in anosmics via two stimulus-delivery systems. The first system consists of the fairly commonly used 270 ml, plastic 'squeeze bottles'. The second system consists of 1900 ml, glass vessels with Teflon tubing and nose-pieces. Although bulkier and more susceptible to mechanical breakage, the glass vessels possess advantages that can allow them to provide 'environmentally realistic' chemosensory thresholds, i.e. thresholds closer in absolute values to those that might be obtained under whole-body exposures. Such advantages include a larger volume of the vapor-source to accommodate whole sniffs, and a tight nose-nose-piece connection to avoid stimulus dilution. The outcome revealed that, for every chemical, the glass vessels provided nasal pungency thresholds significantly lower than those provided by the squeeze bottles. The difference amounted, on average, to a factor of 4.6, though the relative potency of the compounds remained the same under both systems. Additionally, when tested with the highest homologues used here, namely, octyl acetate and 1-octanol, anosmics using the glass vessels had little or no difficulty achieving the criterion for threshold whereas they did have difficulty when using the squeeze bottles.
    Chemical Senses 07/2000; 25(3):285-91. · 3.22 Impact Factor
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    ABSTRACT: Literature data on the solubility of ferrocene in nonaqueous solvents have been combined with the aqueous solubility to give partition coefficients from water to solvents, and have also been combined with the vapour pressure at 298 K to give gassolvent partition coefficients. These two sets of partitions have been analysed through the solvation equations of Abraham to yield values of the solvation descriptors. Ferrocene is shown to have about the same dipolarity/polarisability and hydrogen bond basicity as naphthalene. From the solvation descriptors, various properties of ferrocene have been estimated, including the lipophilicity, the bloodbrain distribution, and the vapour toxicity (as the nasal pungency threshold). de solvatation du et estimation de diverses physico-chimiques et biologiques. Les
    New Journal of Chemistry 01/2000; 24(10):825-829. · 2.97 Impact Factor
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    ABSTRACT: Literature values for the partition of nitric oxide between the gas phase and water and between the gas phase and organic solvents have been combined to yield water–solvent partition coefficients. Analysis of the gas–solvent and water–solvent partition coefficients using the solvation equations of Abraham shows that nitric oxide is only a very weak hydrogen-bond base. The various solvation descriptors of Abraham for nitric oxide can be obtained, and are shown to be similar to other inorganic gases; the descriptors can be used to predict a large number of physicochemical properties of nitric oxide. A key property of nitric oxide is the lipophilicity, as the water–octanol partition coefficient, that we calculate to be quite small at 0.74 (log Poct), about the same as that for argon or nitrogen.
    Journal of the Chemical Society Perkin Transactions 2 01/2000;
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    ABSTRACT: Using 1-butanol and 2-heptanone as stimuli, we measured detectability (i.e., psychometric) functions for the odor, nasal pungency, and eye irritation of these two substances alone and in binary mixtures. Nasal pungency responses were tested in subjects lacking olfaction (i.e., anosmics) for whom odors do not interfere. Eye irritation responses were tested in normosmics and anosmics, and found to be similar in both groups so their results were pooled. When all stimuli--single and mixtures--were transformed into concentration units of one (or the other) chemical, a single function could fit all data from the same sensory end point with a correlation coefficient of 0.91 or higher. The outcome lends support, as a first approximation, to the notion of chemosensory agonism, in the sense of dose additivity, between the members of binary mixtures presented at perithreshold levels.
    Physiology & Behavior 09/1999; 67(2):269-76. · 3.16 Impact Factor

Publication Stats

184 Citations
32.32 Total Impact Points

Institutions

  • 1999–2014
    • University College London
      • Department of Chemistry
      Londinium, England, United Kingdom
  • 1999–2002
    • University of California, San Diego
      • Division of Otolaryngology-Head and Neck Surgery
      San Diego, CA, United States