iPSC-derived cortical neurons to study sporadic Alzheimer disease: A transcriptome comparison with post-mortem brain samples.

Alzheimer's disease (AD) is the most common cause of dementia, characterized by the progressive impairment of cognition and memory loss. Sporadic AD (sAD) represents approximately 95 % of the AD cases and is induced by a complex interplay between genetic and environmental factors called "Alzheimerogens". Heavy metals (e.g. copper) and pesticides (e.g. fipronil) can affect many AD-related processes, including neuroinflammation (considered as AD-inducing factor). Research would benefit from in vitro models to investigate effects of Alzheimerogens. We compared transcriptomics changes in sAD induced pluripotent stem cell (iPSC) derived cortical neurons to differentially expressed genes (DEGs) identified in post-mortem AD brain tissue. These analyses showed that many AD-related processes could be identified in the sAD iPSC-derived neurons, and furthermore, could even identify more DEGs functioning in these processes than post-mortem AD-brain tissue. Thereafter, we exposed the iPSCs to AD-inducing factors (copper(II)chloride, fipronil sulfone and an inflammatory cytokine cocktail). Cytokine exposure induced expression of immune related genes while copper-exposure affected genes involved in lipid and cholesterol metabolism, which are known AD-related processes. Fipronil-exposure did not result in significant transcriptomic changes, although prolonged exposures or higher doses may be necessary. Overall, we show that iPSC-derived cortical neurons can be beneficial in vitro models to identify Alzheimerogens and AD-related molecular mechanisms.

Pesticide residue concentrations in the Belgian total diet, 1991-1993.

In the period 1991-1993, an official study was conducted to measure the presence and evaluate the risk of pesticide residues in plantbased food in the Belgian total diet. Positive samples were subjected to one or more culinary treatments (washing, peeling, steaming, or cooking) to determine the decrease of residues in prepared ready-to-eat food. Thus, better estimates of pesticide residues taken up through consumption were determined and compared with toxicological criteria. Washing did not significantly reduce residues. Peeling fruits removed almost all pesticides. The effects of cooking and steaming varied, depending on the type of food and pesticide.

Monitoring of pesticide residues in fresh vegetables, fruits, and other selected food items in Belgium, 1991-1993.

To estimate the exposure of the Belgian population to food contaminated with pesticide residues and to determine what pesticides people are actually consuming, a total diet study-individual approach-was performed. Fourteen kinds of fruits, 22 kinds of vegetables, and 7 other food items (coffee, drinking water, rice, tea, wine, bran, and wheat flour) were selected as major representatives of the Belgian diet. During the 2 years of study (April 1991-March 1993), about 3,698 samples were analyzed and 21 163 analyses were performed. The first part of this study demonstrates that no residues are found in 31.3% of leafy vegetables, 72.3% of other vegetables, 51.4% of fruits, and 67.2% of other samples. In particular cases, some critical situations still exist, especially for leafy vegetables. Also, contamination of foreign samples is not easy to determine, because origins are not always traceable.

Headspace--gas chromatographic determination of inorganic bromide residues in vegetables.

This study describes a headspace gas-chromatographic method for the quantitative determination of inorganic bromide in vegetables. Different parameters influencing the reaction of the bromide ion into 2-bromoethanol have been investigated. The analysis of 2-bromoethanol is performed by the headspace--electron capture--gas chromatographic technique using a fused silica capillary column CP wax 52 CB. Recoveries of 99.75% +/- 4.1% have been obtained for bromide concentrations of 5 up to 350 mg/kg. Sixty-nine samples have been analysed by this method. The results are in good agreement with the normal bromide extraction method. The absolute detection limit is 2 ng corresponding to 0.5 mg Br-/kg for a slit ratio of 1:10.

Determination of fumigants in cereals and cereal products by capillary gas chromatography.

This study describes two methods for the quantitative determination of the residual fumigants ethylene dichloride (EDC), carbon tetrachloride (CCl4), trichloroethylene (TCE), ethylene dibromide (EDB) and tetrachloroethylene (PCE) in cereals (especially wheat) and other foodstuffs. In the first method, a micro steam distillation- solvent extraction apparatus is used, while the second method is based on a headspace technique. For the quantitative determination of carbon tetrachloride in cereals, the multiple headspace technique is not retained because it is too time-consuming. The analysis of the different fumigants is performed by electron-capture gas chromatography, using a fused silica capillary column, CP sil 8 CB. With the steam distillation-solvent extraction method, recoveries from 95.9% to 100.5% are obtained for the fumigants, added at two different levels. The standard deviation varies between 1.1% and 6%. Using the simple headspace technique, recoveries from 73.5% to 85.1% with a standard deviation of between 1.7% and 6.6% have been reached for the fumigants in cereals fortified at two different levels. The absolute detection limits for the five fumigants EDC, CCl4, TCE, EDB and PCE, in both methods, are 30, 0.25, 1.1, and 0.5 pg, respectively.

Residues of organochlorine pesticides in human fat in Belgium.

In 1975, 60 samples of human body fat taken during the course of routine examinations by pathologists were analysed for organochlorine pesticide residues. The mean detected concentrations are 1.36 ppm for HCB, 0.76 ppm for betaHCH, 0.38 ppm for heptachlor epoxide, 0.26 ppm for dieldrin, 6.50 ppm for ppDDE, 0.27 ppm for ppDDD and 1.52 ppm for ppDDT. By comparing these results with earlier studies in 1969 and 1966 a decrease in the total HCH and ppDDT content and an increase in the dieldrin and heptachlor epoxide content is observed. HCB was not determined in earlier studies.

Residues of quintozene, its contaminants and metabolites in soil, lettuce, and witloof-chicory, Belgium--1969-74.

Authors studied contamination of soils used to raise lettuce in greenhouses and witloof-chicory (French endive) in forcing beds. The crops had been treated with the fungicide quintozene; residues detected included quintozene, its technical impurities and metabolites hexachlorobenzene, pentachlorobenzene, pentachloroaniline, and pentachlorothioanisole. Analyses of 72 soil samples indicated that soils remain contaminated with these chemicals one or more years after application. This is attributed to the high persistence of quintozene, its impurities and metabolites, and the almost annual application of the fungicide. Analyses of the crops show that quintozene, hexachlorobenzene, and pentachloroaniline are taken up from contaminated soils, especially by lettuce. Pentachlorothioanisole, although present in the soils, was not detected in the crops.

Residues of quintozene, hexachlorobenzene, dichloran and pentachloroaniline in soil and lettuce.

The results are described of the residue determination of quintozene, hexachlorobenzene, dichloran and pentachloroaniline in soil and lettuce after application of different quantities of quintozene just before and two weeks after planting. The results indicate that quintozene, hexachlorobenzene and dichloran are readily taken up by lettuce from the soil and that quintozene is metabolised to pentachloroaniline resulting in residues of these compounds in lettuce.