Enhancement of hepatic microsomal esterase activity following soman pretreatment in guinea pigs

Soman (pinacolyl methylphosphonofluoridate), a highly toxic organophosphate compound, has been found to be a strong inhibitor of hepatic microsomal carboxylesterase in vitro, but an enhancer of carboxylesterase when administered in vivo. In response to this paradoxical observation, the objective of this study was to determine if soman could cause true enhancement of the metabolism of drugs in the guinea pig and, if so, to characterize the enhanced enzyme activity. Following the pretreatment of guinea pigs with 90% LD50 soman, enhancement of microsomal esterase activity was noted 12 and 24 hr after pretreatment. Using Michaelis-Menten enzyme kinetic studies, enhancement was found to occur with liver carboxylesterase and procaine esterase, but not with aniline hydroxylase. Since the soman-enzyme complex was known to undergo aging with the release of pinacolyl alcohol and the subsequent formation of pinacolone, the effects of these metabolites on the activity of liver microsomal enzymes in vitro were explored. Pinacolone and pinacolyl alcohol produced enzyme enhancement in vitro in a manner similar to that produced by soman pretreatment. These effects were compared with those made by acetone in the same incubations, since the enhancing influence of acetone has already been well documented. Similarity was found between the in vitro effects of acetone and the effects of pinacolone and pinacolyl alcohol. Lastly, the in vivo effects of pinacolone on the activities of the same liver microsomal enzymes were studied following pretreatment of the guinea pigs with 90% LDLo (lowest published lethal dose) pinacolone. Pretreating guinea pigs with pinacolone prior to killing them enhanced liver microsomal carboxylesterase and procaine esterase activities, but had no effect on microsomal aniline hydroxylase activity. This pattern of enzyme enhancement was similar to that observed after soman pretreatment. Therefore, soman was found to enhance hepatic microsomal esterase activity in the guinea pig in a manner similar to that seen with its metabolites, as well as acetone. This information may give insight into how the efficacy and toxicity of therapeutic drugs, other xenobiotics, and endogenous materials may be altered in individuals who survive an exposure to soman.     

Measurement of styrene oxide in polystyrenes, estimation of migration to foods, and reaction kinetics and products in food simulants

The concentration of styrene-7,8-oxide has been measured in nine base resins and 16 samples of polystyrene articles intended for food contact. The epoxide was not detected in the resins (limit of detection 0.5 mg/kg) but was found in 11 of the 16 packaging samples at up to 2.9 mg/kg. Assuming that the propensity of styrene oxide to migrate is the same as styrene monomer, and using existing survey data for styrene monomer in packaging and foods, the migration levels expected for styrene oxide were calculated. Estimates were from 0.002 to 0.15 microgram/kg styrene oxide in foods. The stability of styrene oxide in the four standard EU food simulants was studied at 40, 100, 150 and 175 degrees C, to establish the transformation products to be expected following migration testing. The half-life at 40 degrees C in distilled water, 15% aqueous ethanol, 3% aqueous acetic acid and olive oil was 15, 23, < 1, > 2000 hr, respectively. The principal product was the diol from hydrolysis of the epoxide group. Ring opening in aqueous ethanol simulant gave the diol and also the glycol monoethyl ether. It is concluded that this instability of styrene oxide will reduce concentrations in foods, from an already low migration level to even lower levels with the formation of hydrolysis products that are less toxic than the parent epoxide.     

The metallurgical pretreatment and protective oxidation of a 9.75% Cr-Fe alloy in CO2

The variation of the structure and composition of the oxide formed in CO₂ on cold worked material with distance from the oxide-gas interface has been studied using specimens ion beam thinned for the transmission electron microscope. The results presented have been compared with those previously reported for the protective oxidation of an annealed alloy in CO₂. The oxide formed is duplex and the inner oxide which differs from the fine grained oxide on the annealed material consists of larger columnar grains. Carbon, from the oxidation reaction, is injected into the metal forming M₂C and M₂₃C₆ carbides in addition to the M₇C₃ carbides exclusively formed in the annealed alloy. The oxide-metal interface is well defined and dependent on the grain structure of the metal. This feature together with the larger grain size of the oxide may result in the reduction in the oxidation rate for cold worked alloys reported by other workers.     

Evaluation of a predictive mathematical model of di-(2-ethylhexyl) adipate plasticizer migration from PVC film into foods

The diffusion coefficient of the plasticizer di-(2-ethylhexyl)adipate (DEHA) in Cheddar cheese (Df) was determined by measuring the extent to which DEHA penetrated cheese that was placed in intimate contact with artificially DEHA-contaminated cheese. Slices (20 microns) of cheese from the boundary layer, into which DEHA had migrated, were microtomed at -40 degrees C, and analyzed for DEHA by gas chromatography (GC). Mean values of Df determined by graph fitting experimental and calculated data were 1.5 x 10(-9) cm2 s-1 at 5 degrees C and 3.0 x 10(-8) cm2 s-1 at 25 degrees C. The partition coefficient (K) of DEHA between cheese and PVC film was derived from the partition coefficients of DEHA between acetonitrile (ACN) and cheese lipid, ACN and cheese solid, and ACN and PVC film. The mean values of K between cheese and PVC film were estimated to be 0.70 at 5 degrees C and 0.58 at 25 degrees C. The estimated values of Df and K were then used in a mathematical model (Till et al. 1982) to predict migration levels of DEHA into cheese. Good agreement with previously published experimental data was obtained. Extrapolation of the prediction of DEHA migration into fatty foods, such as salami and avocado, was also successful (ratio of experimental to predicted results within a factor of two). The values of Df and K for cheese are, however, inappropriate for modelling non-fatty foods such as meat, cakes, fruit and vegetables. Predicted values for these foods were typically 3-10-fold too high. More accurate predictions would probably be obtained if values of Df more relevant to these foods are used. The predictions were relatively insensitive to the value of K.     

Migration of mineral hydrocarbons into foods. 1. Polystyrene containers for hot and cold beverages.

Mineral hydrocarbons are used as processing aids at levels between 0.3 and 3% by weight in crystal polystyrene articles, the food contact uses of which include the dispensing of hot and cold beverages from automatic machines as well as in 'fast-food' and catering establishments. The levels of migration of mineral hydrocarbons from polystyrene cups and glasses have been measured into aqueous food simulants as well as lager, beer, cola, sparkling apple juice, lemon barley water, coffee, hot chocolate, tea, lemon tea and chicken soup. For the cold beverages and simulants, no migration above 0.1 mg/kg was observed, and for the hot beverages and simulants no result greater than 0.5 mg/kg. Analysis was by capillary gas chromatography, using hydrocarbon internal standards calibrated against mineral hydrocarbon reference standards.     

Comparative study of artists and nonartists on the maitland graves design judgment test.

Administered the maitland graves design judgment test to 229 male and 236 female nonart students and 519 male and 478 female art students. Only very slight differences were observed between groups. Following the lines of a previous factor analysis of the test, scores were derived for 3 subsets of designs (symmetrical, 3-dimensional, complex). These scores were negligible correlated with each other. Conspicuous differences between artists and controls were only found for the symmetrical set, and scores on this set were more homogeneous for artists than for controls. The use of overall scores on a heterogeneous test is criticized, and the development of a more homogeneous test based on symmetrical designs only is suggested. An explanation is suggested for the differences in results reported by graves and the present study. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The pattern of acceptance by Blacks of family planning facilities in relation to socio-economic status

Two factors which are said to increase the acceptability of family planning in a developing country are, firstly, the ready availability of the facilities and, secondly, the raising of the socio-economic level of the community. This survey reports the effects on family planning of increasing socio-economic status on the one hand, and of urbanisation without an associated increase in the socio-economic level on the other. It is concluded that, although socio-economic status has some effect on family planning, it has a greater effect on the survival rate of children. Urbanisation, however, with family planning facilities more readily available, exerts a stronger influence upon the acceptance of family planning than socio-economic status.     

Generation of bipolar electric fields during industrial handling of powders

This paper presents the results of some field tests that were carried out to determine the electric fields generated due to bipolar charging that occurs during the filling of a container with conveyed powders in an industrial setting. Approximately 1000 kg of pneumatically conveyed powder was allowed to fall into a cubically shaped container made out of woven fibreglass cloth that was placed on a metallic base electrically connected to ground. During the filling operation, the electric fields at three points close to the outside surface of the container were measured with a calibrated electrostatic probe. The results show that as the container is being filled, the mass of powder that accumulates in the lower part generates outward directed positive electric fields. In contrast, the shrinking, unfilled, upper space in the container generates considerably stronger outward directed negative electric field at the surface. At the level of the powder filling the container, the outward directed electric field was approximately zero. As the container fills, the zero electric field level moves upwards and the negative electric field disappears leaving the entire surface with a positive electric field. The net charge to mass ratio of the conveyed powder was measured in the order of 1.5 E-10 C/g, while falling into the container. Some of the generated negative electric fields at the surface were as high as 30 kV/cm. These results confirm previous measurements with other powders that showed that in a poly-disperse mixture, fine particles tend to charge negatively whereas coarser particles charge positively.