Genotoxicity and mutagenicity assessment of food contaminant mixtures present in the French diet

Through diet, people are exposed simultaneously to a variety of contaminants (e.g. heavy metals, mycotoxins, pesticides) that could have combined adverse effects on human health. A previous study identified six main mixtures of food contaminants to which French adult consumers are exposed. These complex mixtures are comprised of 11 to 19 chemicals that have numerous toxic properties. In the present study, we investigated the genotoxic effects of these food contaminants, as single molecules and in mixtures that reflect their occurrence in the French diet, using the γH2AX assay in two human cell lines (HepG2, LS-174 T). Results of detailed analysis of the 49 individual contaminants (including 21 tested in this study) demonstrated a positive genotoxic response to 14 contaminants in HepG2 and 12 in LS-174 T cells. Next, our results indicated that two mixtures out of six triggered significant γH2AX induction after 24 hr of treatment, at concentrations for which individual compounds did not induce any DNA damage, suggesting more than additive interactions between chemicals. γH2AX positive mixtures were then tested for mutagenicity with the innovative in vitro PIG-A assay in HepG2 cells coupled with the soft agar colony formation assay. The two γH2AX positive mixtures led to a significant increase in the frequency of PIG-A GPI-deficient cells and in the number of colonies formed in soft agar. In conclusion, our study demonstrates that two mixtures of contaminants present in the French diet induce genotoxicity and mutagenicity, and that the combined effects of single molecules present in these mixtures are likely not additive, highlighting potential problems for hazard assessment of mixtures. Environ. Mol. Mutagen. 59:742-754, 2018. © 2018 Wiley Periodicals, Inc.

Immediate Hypersensitivity to Contrast Agents: The French 5-year CIRTACI Study

BACKGROUND

Iodinated and gadolinium-based contrast media (ICM; GBCM) induce immediate hypersensitivity (IH) reactions. Differentiating allergic from non-allergic IH is crucial; allergy contraindicates the culprit agent for life. We studied frequency of allergic IH among ICM or GBCM reactors.

METHODS

Patients were recruited in 31 hospitals between 2005 and 2009. Clinical symptoms, plasma histamine and tryptase concentrations and skin tests were recorded. Allergic IH was diagnosed by intradermal tests (IDT) with the culprit CM diluted 1:10, "potentially allergic" IH by positive IDT with pure CM, and non-allergic IH by negative IDT.

FINDINGS

Among 245 skin-tested patients (ICM = 209; GBCM = 36), allergic IH to ICM was identified in 41 (19.6%) and to GBCM in 10 (27.8%). Skin cross-reactivity was observed in 11 patients with ICM (26.8%) and 5 with GBCM (50%). Allergy frequency increased with clinical severity and histamine and tryptase concentrations (p < 0.0001). Cardiovascular signs were strongly associated with allergy. Non-allergic IH was observed in 152 patients (62%) (ICM:134; GBCM:18). Severity grade was lower (p < 0.0001) and reaction delay longer (11.6 vs 5.6 min; p < 0.001). Potentially allergic IH was diagnosed in 42 patients (17.1%) (ICM:34; GBCM:8). The delay, severity grade, and mediator release were intermediate between the two other groups.

INTERPRETATION

Allergic IH accounted for < 10% of cutaneous reactions, and > 50% of life-threatening ones. GBCM and ICM triggered comparable IH reactions in frequency and severity. Cross-reactivity was frequent, especially for GBCM. We propose considering skin testing with pure contrast agent, as it is more sensitive than the usual 1:10 dilution criteria.

Genotoxicity of 11 heavy metals detected as food contaminants in two human cell lines

Heavy metals, such as arsenic (As), antimony (Sb), barium (Ba), cadmium (Cd), cobalt (Co), germanium (Ge), lead (Pb), nickel (Ni), tellurium (Te), and vanadium (V) are widely distributed in the environment and in the food chain. Human exposure to heavy metals through water and food has been reported by different international agencies. Although some of these heavy metals are essential elements for human growth and development, they may also be toxic at low concentrations due to indirect mechanisms. In this study, the genotoxic and cytotoxic properties of 15 different oxidation statuses of 11 different heavy metals were investigated using high-throughput screening (γH2AX assay) in two human cell lines (HepG2 and LS-174T) representative of target organs (liver and colon) for food contaminants. Base on their lowest observed adverse effect concentration, the genotoxic potency of each heavy metal in each cell line was ranked in decreasing order, NaAsO₂  > CdCl₂  > PbCl₂ (only in LS-174T cells) > As₂ O₅  > SbCl₃  > K₂ TeO₃  > As₂ O₃ . No significant genotoxicity was observed with the other heavy metals tested. Cell viability data indicate that several heavy metals (As, Cd, Co, Ni, Sb, and Te) induce cytotoxicity at high concentrations, whereas an increase in the number of cells was observed for lead concentrations >100 µM in both cell lines tested, suggesting that lead stimulates cell growth. All these results highlight the possible human health hazards associated with the presence of heavy metals present in food. Environ. Mol. Mutagen. 59:202-210, 2018. © 2017 Wiley Periodicals, Inc.

Understanding leachate flow in municipal solid waste landfills by combining time-lapse ERT and subsurface flow modelling - Part II: Constraint methodology of hydrodynamic models

Leachate recirculation is a key process in the operation of municipal solid waste landfills as bioreactors. To ensure optimal water content distribution, bioreactor operators need tools to design leachate injection systems. Prediction of leachate flow by subsurface flow modelling could provide useful information for the design of such systems. However, hydrodynamic models require additional data to constrain them and to assess hydrodynamic parameters. Electrical resistivity tomography (ERT) is a suitable method to study leachate infiltration at the landfill scale. It can provide spatially distributed information which is useful for constraining hydrodynamic models. However, this geophysical method does not allow ERT users to directly measure water content in waste. The MICS (multiple inversions and clustering strategy) methodology was proposed to delineate the infiltration area precisely during time-lapse ERT survey in order to avoid the use of empirical petrophysical relationships, which are not adapted to a heterogeneous medium such as waste. The infiltration shapes and hydrodynamic information extracted with MICS were used to constrain hydrodynamic models in assessing parameters. The constraint methodology developed in this paper was tested on two hydrodynamic models: an equilibrium model where, flow within the waste medium is estimated using a single continuum approach and a non-equilibrium model where flow is estimated using a dual continuum approach. The latter represents leachate flows into fractures. Finally, this methodology provides insight to identify the advantages and limitations of hydrodynamic models. Furthermore, we suggest an explanation for the large volume detected by MICS when a small volume of leachate is injected.

Understanding leachate flow in municipal solid waste landfills by combining time-lapse ERT and subsurface flow modelling - Part I: Analysis of infiltration shape on two different waste deposit cells

Landfill bioreactors are based on an acceleration of in-situ waste biodegradation by performing leachate recirculation. To quantify the water content and to evaluate the leachate injection system, in-situ methods are required to obtain spatially distributed information, usually electrical resistivity tomography (ERT). In a previous study, the MICS (multiple inversions and clustering strategy) methodology was proposed to improve the hydrodynamic interpretation of ERT results by a precise delimitation of the infiltration area. In this study, MICS was applied on two ERT time-lapse data sets recorded on different waste deposit cells in order to compare the hydrodynamic behaviour of leachate flow between the two cells. This comparison is based on an analysis of: (i) the volume of wetted waste assessed by MICS and the wetting rate, (ii) the infiltration shapes and (iii) the pore volume used by the leachate flow. This paper shows that leachate hydrodynamic behaviour is comparable from one waste deposit cell to another with: (i) a high leachate infiltration speed at the beginning of the infiltration, which decreases with time, (ii) a horizontal anisotropy of the leachate infiltration shape and (iii) a very small fraction of the pore volume used by the leachate flow. This hydrodynamic information derived from MICS results can be useful for subsurface flow modelling used to predict leachate flow at the landfill scale.

Influence of the geomembrane on time-lapse ERT measurements for leachate injection monitoring

Leachate recirculation is a key process in the operation of municipal waste landfills as bioreactors. To quantify the water content and to evaluate the leachate injection system, in situ methods are required to obtain spatially distributed information, usually electrical resistivity tomography (ERT). However, this method can present false variations in the observations due to several parameters. This study investigates the impact of the geomembrane on ERT measurements. Indeed, the geomembrane tends to be ignored in the inversion process in most previously conducted studies. The presence of the geomembrane can change the boundary conditions of the inversion models, which have classically infinite boundary conditions. Using a numerical modelling approach, the authors demonstrate that a minimum distance is required between the electrode line and the geomembrane to satisfy the good conditions of use of the classical inversion tools. This distance is a function of the electrode line length (i.e. of the unit electrode spacing) used, the array type and the orientation of the electrode line. Moreover, this study shows that if this criterion on the minimum distance is not satisfied, it is possible to significantly improve the inversion process by introducing the complex geometry and the geomembrane location into the inversion tools. These results are finally validated on a field data set gathered on a small municipal solid waste landfill cell where this minimum distance criterion cannot be satisfied.

Use of the γH2AX assay for assessing the genotoxicity of polycyclic aromatic hydrocarbons in human cell lines

The development of in vitro genotoxic assays as an alternative method to animal experimentation is of growing interest in the context of the implementation of new regulations on chemicals. However, extrapolation of toxicity data from in vitro systems to in vivo models is hampered by the fact that in vitro systems vary in their capability to metabolize chemicals, and that biotransformation can greatly influence the experimental results. Therefore, much attention has to be paid to the cellular models used and experimental conditions. Polycyclic aromatic hydrocarbons (PAHs) are carcinogenic ubiquitous pollutants. Human exposure to PAHs is mainly from food origin. In this study, a detailed analysis of the biotransformation capabilities of three human cell lines commonly used for in vitro testing (HepG2, ACHN and Caco-2) was undertaken using 3 model PAHs (benzo(a)pyrene [B(a)P], fluoranthene [FLA] and 3-methylcholanthrene [3-MC]). Concomitantly the genotoxicity of these PAHs was investigated in different cell lines, using a new genotoxic assay (H2AX) in 96-well plates. The metabolic rates of B(a)P, FLA and 3-MC were similar in HepG2 and Caco-2 cell lines, respectively, though with the production of different metabolites. The ACHN cell line was shown to express very limited metabolic capabilities. We demonstrated that the PAHs having a high metabolic rate (B(a)P and 3-MC) were genotoxic from 10(-7) molar in both HepG2 and Caco-2 cells. The present study shows that H2AX measurement in human cell lines competent for the metabolism, is an efficient and sensitive genotoxic assay requiring less cells and time than other currently available tests.

[Pulmonary embolism and sibilant types of chronic obstructive pulmonary disease decompensations]

Pulmonary Embolism (PE) poses an important diagnostic problem in patients with chronic obstructive pulmonary disease (COPD). Indeed PE may aggravate the already precarious respiratory state of these fragile patients. Moreover, these two conditions share common symptoms: dyspnoea, wheezing, pleural pain, haemoptysis, palpitations and signs of right cardiac insufficiency. In two studies, one retrospective and the other prospective, we investigated the incidence of PE in patients with non-infective exacerbations of their COPD. The retrospective study was carried out over two years and involved 50 COPD patients with non-infective respiratory exacerbations. In this population, 10 patients out of 50 (20%) had a documented PE. No predictive factor was identified. The prospective study was conducted over one year and COPD patients admitted to hospital with exacerbations were included in the study if they had a positive D-dimer blood test and no evidence of acute respiratory infection. 31 patients were studied with Doppler ultra-sound examination of the legs and a lung perfusion scan. The presence or absence of PE was determined and the two groups were compared. 9 patients out of 31 (29%) had a documented PE. Six of these nine patients had a deep venous thrombosis (DVT). Two predictive factors of PE were identified: existence of a DVT and a significant fall in PaO(2) from baseline state (DeltaPaO(2) > 22 mmHg). We conclude that PE is a frequent (20 to 30%) of non-infective respiratory decompensation in COPD patients. Faced with an unexplained respiratory exacerbation in these patients, a lung perfusion scan should be routinely undertaken to rule out a PE when the D-dimers are positive.

Alterations of the DNA repair gene OGG1 in human clear cell carcinomas of the kidney

The OGG1 gene, which codes for a DNA repair protein with antimutator activity, is located on chromosome 3p25, a frequent site of allelic deletions in many types of human tumors, including renal clear cell cancers. We present the analysis of 99 renal tumors for alterations in the OGG1 gene to determine its association with tumorigenesis. Loss of heterozygosity in the 3p25 region was found for 85% of the informative cases. We detected somatic missense mutations of the OGG1 gene in 4 of the 99 tumor samples. Biochemical analysis of the mutant proteins revealed that a substitution at codon 46 impairs the enzymatic activity. We also describe the occurrence of several polymorphisms as well as aberrantly spliced OGG1 transcripts.

Effect of single mutations in the OGG1 gene found in human tumors on the substrate specificity of the Ogg1 protein

We have investigated the effect of single amino acid substitutions of conserved arginines on the catalytic activities of the human Ogg1 protein (alpha-hOgg1-Ser(326)) (wild-type alpha-hOgg1). Mutant forms of hOgg1 with mutations Arg(46)-->Gln (alpha-hOgg1-Gln(46)) and Arg(154)-->His (alpha-hOgg1-His(154)) have previously been identified in human tumors. The mutant proteins alpha-hOgg1-Gln(46) and alpha-hOgg1-His(154) were expressed in Escherichia coli and purified to homogeneity. The substrate specificities of these proteins and wild-type alpha-hOgg1 were investigated using gamma-irradiated DNA and the technique of gas chromatography/isotope-dilution mass spectrometry. All three enzymes excised 2,6-diamino-4-hydroxy-5-formamidopyrimidine (FapyGua) and 8-hydroxyguanine (8-OH-Gua) from gamma-irradiated DNA containing a multiplicity of base lesions. Michaelis-Menten kinetics of excision were measured. Significant differences between excision kinetics of these three enzymes were observed. Excision of FapyGua and 8-OH-Gua by wild-type alpha-hOgg1 was greater than that by alpha-hOgg1-Gln(46) and alpha-hOgg1-His(154). The latter mutant protein was less active than the former. The diminished activity of the mutant proteins was more pronounced for 8-OH-Gua than for FapyGua. Cleavage assays were also performed using (32)P-labeled 34mer oligonucleotide duplexes containing a single 8-OH-Gua paired to each of the four DNA bases. The results obtained with the oligonucleotide containing the 8-OH-Gua/Cyt pair were in good agreement with those observed with gamma-irradiated DNA. Wild-type alpha-hOgg1 and its mutants repaired the three mismatches less efficiently than the 8-OH-Gua/Cyt pair. The substitution of Arg(154), in addition to diminishing the activity on 8-OH-Gua, relaxes the selectivity found in the wild-type alpha-hOgg1 for the base opposite 8-OH-Gua. Taken together the results show that the mutant forms alpha-hOgg1-Gln(46) and alpha-hOgg1-His(154) found in human tumors are defective in their catalytic capacities.

[Value of imaging in early diagnosis of peripheral vein tumors]

Peripheral venous tumors are uncommon and their delayed clinical expression leads to poor prognosis. We report a series of 7 cases including 6 leiomyosacromas and 1 hemangioendothelioma. Duplex Doppler and MR imaging appeared to be best suited for diagnosis, allowing an evaluation of extension and an analysis of associated endoluminal thrombi. These imaging techniques help guide surgery and improve prognosis.

[Carcinoid tumors of the rectum. Apropos of 2 cases with metastases]

We are reporting two cases of carcinoid tumors of the rectum treated surgically. In both cases, there were nodes metastases and in one case liver metastases without carcinoid syndrome. Carcinoid tumors of the rectum are rare and usually asymptomatic; metastases are essentially located in the lymph nodes and the liver.

[Biermer's disease and selective IgA deficiency. Apropos of a case]

The authors report a case of pernicious anaemia in a 41-year old white man; this case has particular features: rise in mean corpuscular volume, neurological manifestation 8 and 2 years respectively before diagnosis, association with selective IgA deficiency. Relations between pernicious anaemia and immunoglobulin deficiency are discussed.

[Gallbladder atony and celiac disease in adults. Radiographic and echographic study of 15 cases]

Gallbladder emptying was evaluated in 15 adult celiac disease patients by oral cholecystography or ultrasonography, after fatty meal or cholecystokinin stimulation. Gallbladder inertia was found in 13 cases. Our study agrees with previously reported results; however it is the first one in which this abnormality was demonstrated by ultrasonography. Our findings may suggest that gallbladder inertia is due to duodenal release of an inactive endogenous cholecystokinin. Control studies demonstrates that gallbladder inertia is reversible after gluten-free diet, recurs with relapse, and thus represents a true celiac disease sign, and not an associated condition. Finally, our cases suggest that gallbladder inertia may be radiologically evident before clinical features of malabsorption become apparent. Awareness of this possibility may persuade the radiologist to research in this condition an occult celiac disease.

[Choledochocele in the adult]

Choledochocele are cystic polypoid lesions of the end portion of the common bile duct. The occurrence of choledochocele is 4 p. cent among choledochal cysts. One case is presented in a 78-year-old woman. The treatment was surgical excision. This case was unusual by the age of the patient and by the diagnostic missed at the time of a cholecystectomy performed one year previously.

[Choledochocele in adults]

Choledochocele are cystic polypoid lesions of the end portion of the common bile duct. The occurrence of choledochocele is 4 p. cent among choledochal cysts. One case is presented in a 78-year-old woman. The treatment was surgical excision. This case was unusual by the age of the patient and by the diagnosis missed at the time of a cholecystectomy performed one year previously.

[Folate and the nervous system (author's transl)]

The responsibility of the folate deficiency in some neuropsychiatric disorders is recent knowledge. The role of the folate on the nervous system is not yet well definite, but the action on the metabolism of the amino-acids, on the purine and the pyrimidine synthesis and on the metabolism of the catecholamins are certainly essential. The neuropsychiatric diseases secondary to the folate deficiency are numerous: dementia, schizophrenia like syndromes, insomnia, irritability, forgetfulness, endogenous depression, organic psychosis, pueperal psychosis, peripheral neuropathy, myelopathy (spinal cord syndrome and/or pyramidal tract damage), restless legs syndrome. Clinically the diagnosis may be difficult with sub acute combined degenration secondary to the pernicious anaemia, and the dosage of the folate (in serum, in red-cells and in cerebrospinal fluid) is necessary. The congenital defects in the uptake or utilization of the folate are associated with neuropsychiatric disturbances. The treatment is easy and safe if the vitamin B12 deficiency is eliminated and if employed with caution in epileptic patients because folate can induced seizures.

[Complications of digestive involvement in CRST syndrome. 3 cases (author's transl)]

In CRST syndrome, latent oesophageal involvement is common but not usually associated with any clinical manifestations. Involvement of the small intestine is rare. In three patients there occurred severe complications related to digestive involvement in the condition. In one case, involvement of the small intestine was associated with functional obstruction. In the other two patients, oesophageal involvement progressed to very tight stenosis of the lower end of the eosophagus. The generally accepted bening nature of this form of scleroderma must therefore be questioned.

[Duhring's and coeliac's diseases (author's transl)]

An atrophy of villi without digestive troubles is found in a 3 1/2 years old boy with a typical Duhring's disease. This observation proves the interest to research an enteropathy in case of dermatitis herpetiformis, and on the other hand the gluten free diet's efficacity on the cutaneous lesions. The authors consider cutaneous lesions's pathogeny and the antigenic relations between these two diseases.