Multivariate analysis and digital twin modelling: Alternative approaches to evaluate molecular relaxation in photoacoustic spectroscopy

A comparative analysis of two different approaches developed to deal with molecular relaxation in photoacoustic spectroscopy is here reported. The first method employs a statistical analysis based on partial least squares regression, while the second method relies on the development of a digital twin of the photoacoustic sensor based on the theoretical modelling of the occurring relaxations. Methane detection within a gas matrix of synthetic air with variable humidity level is selected as case study. An interband cascade laser emitting at 3.345 µm is used to target methane absorption features. Two methane concentration ranges are explored targeting different absorptions, one in the order of part-per-million and one in the order of percent, while water vapor absolute concentration was varied from 0.3 % up to 2 %. The results achieved employing the detection techniques demonstrated the possibility to efficiently retrieve the target gas concentrations with accuracy > 95 % even in the case of strong influence of relaxation effects.

Observational trial of safe food handling behavior during food preparation using the example of Campylobacter spp

Campylobacter infections are one of the most prominent worldwide food-related diseases. The primary cause of these infections is reported to be improper food handling, in particular cross-contamination during domestic preparation of raw chicken products. In the present study, food handling behaviors in Austria were surveyed and monitored, with special emphasis on Campylobacter cross-contamination. Forty participants (25 mothers or fathers with at least one child ≤10 years of age and 15 elderly persons ≥60 years of age) were observed during the preparation of a chicken salad (chicken slices plus lettuce, tomato, and cucumber) using a direct structured observational scoring system. The raw chicken carcasses and the vegetable part of the salad were analyzed for Campylobacter. A questionnaire concerning knowledge, attitudes, and interests related to food safety issues was filled out by the participants. Only 57% of formerly identified important hygiene measures were used by the participants. Deficits were found in effective hand washing after contact with raw chicken meat, but proper changing and cleaning of the cutting board was noted. Campylobacter was present in 80% of raw chicken carcasses, albeit the contamination rate was generally lower than the limit of quantification (10 CFU/g). In the vegetable part of the prepared product, no Campylobacter was found. This finding could be due to the rather low Campylobacter contamination rate in the raw materials and the participants' use of some important food handling behaviors to prevent cross-contamination. However, if the initial contamination had been higher, the monitored deficits in safe food handling could lead to quantifiable risks, as indicated in other published studies. The results of the observational trial and the questionnaire indicated knowledge gaps in the food safety sector, suggesting that further education of the population is needed to prevent the onset of foodborne diseases.

Coffee consumption protects human lymphocytes against oxidative and 3-amino-1-methyl-5H-pyrido[4,3-b]indole acetate (Trp-P-2) induced DNA-damage: Results of an experimental study with human volunteers

Aim of the study was to investigate the impact of coffee on DNA-stability in humans. DNA-damage was monitored in lymphocytes of eight individuals with single cell gel electrophoresis assays before and after consumption of 600 ml coffee (400 ml paper filtered and 200 ml metal filtered/d) for five days. Under standard conditions, no alteration of DNA-migration was seen, but a strong reduction of DNA-migration attributable to endogenous formation of oxidised purines and pyrimidines was detected with restriction enzymes; furthermore DNA-damage caused by reactive oxygen radicals (H2O2 treatment) and by the heterocyclic aromatic amine 3-amino-1-methyl-5H-pyrido[4,3-b]indole-acetate was significantly reduced after coffee consumption by 17% and 35%, respectively. Also in in vitro experiments, inhibition of H2O2 induced DNA-damage was observed with coffee at low concentrations (<or= 25 microl/ml) whereas the diterpenoids cafestol and kahweol caused only marginal effects indicating that the effects of coffee are due to scavenging effects of other constituents. Enzyme measurements showed that additionally induction of antioxidant enzymes may play a role: while the activity of glutathione peroxidase was only marginally increased after coffee consumption, a significant (38%) increase of superoxide dismutase activity was detected. Comparisons with results of earlier studies suggest that coffee consumption may prevent oxidative DNA-damage to a higher extent as diets enriched in fruits and vegetables.

Benzalkonium chloride (BAC) and dimethyldioctadecyl-ammonium bromide (DDAB), two common quaternary ammonium compounds, cause genotoxic effects in mammalian and plant cells at environmentally relevant concentrations

Quaternary ammonium compounds (QACs) are cationic surfactants that are widely used as disinfectants. In the present study, we tested two important representatives, namely, benzalkonium chloride (BAC) and dimethyldioctadecyl-ammonium bromide (DDAB) in four genotoxicity tests, namely, in the Salmonella/microsome assay with strains TA 98, TA 100 and TA 102, in the single-cell gel electrophoresis (SCGE) assay with primary rat hepatocytes and in micronucleus (MN) assays with peripheral human lymphocytes and with root tip cells of Vicia faba. In the bacterial experiments, consistently negative results were obtained in the dose range between 0.001 and 110 microg per plate in the presence and absence of metabolic activation while significant induction of DNA migration was detected in the liver cells. With BAC, a moderate but significant effect was found with an exposure concentration of 1.0 mg/l while DDAB caused damage at lower doses (0.3 mg/l). The effects were not altered when the nuclei were treated with formamidopyridine glycosylase, indicating that they are not due to formation of oxidized purines. The MN assays with blood cells were carried out under identical conditions to the SCGE experiments and a significant increase was seen at the highest dose levels (BAC: 1.0 and 3.0 mg/l; DDAB: 1 mg/l). Both compounds also caused significant induction of MN as well as inhibition of cell division in plant cells, the lowest effective levels were 1.0 and 10 mg/l for DDAB and BAC, respectively. Our findings show that both chemicals induce moderate but significant genotoxic effects in eukaryotic cells at concentrations which are found in wastewaters and indicate that their release into the environment may cause genetic damage in exposed organisms. Furthermore, the direct contact of humans to QAC-containing detergents and pharmaceuticals that contain substantially higher concentrations than those which were required to cause effects in eukaryotic cells in the present study should be studied further in regard to potential DNA-damaging effects in man.

In vitro effects of meloxicam with or without doxorubicin on canine osteosarcoma cells

Cyclooxygenase (COX) inhibitors, already widely used to reduce fever, inflammation and pain, are under increasing consideration as potential agents for the prevention and treatment of neoplasia. As COX-2 was detected in human and canine osteosarcomas, we have evaluated the effect of the preferential COX-2 inhibitor meloxicam on an established D-17 canine osteosarcoma cell line, which expressed, as well as COX-1 and COX-2 also COX-3 (as demonstrated by Western blot). An XTT proliferation kit was used to assess surviving cells after drug treatment. At low concentrations (1, 2, 4 and 10 microm) meloxicam caused an increase in cell numbers while a marked anti-proliferative effect was observed at higher concentrations (100, 200 microm) after 3 days and also 3 weeks of incubation. The chemotherapeutic drug doxorubicin showed a cytotoxic effect at all concentrations (60-1920 nm). Exposure of tumour cells to combinations of meloxicam and doxorubicin revealed synergistic effects (with 240 nm doxorubicin), as well as sub-additive and antagonistic results, especially if combined with concentrations of meloxicam typically found in serum. Care should be taken in concluding, on the basis of one in vitro study, that meloxicam does not have a role in the treatment of canine osteosarcomas given that the results from in vivo studies may differ.

Methods for the detection of antioxidants which prevent age related diseases: a critical review with particular emphasis on human intervention studies

It is well documented that reactive oxygen species (ROS) are involved in the aetiology of age related diseases. Over the last decades, strong efforts have been made to identify antioxidants in human foods and numerous promising compounds have been detected which are used for the production of supplements and functional foods. The present paper describes the advantages and limitations of methods which are currently used for the identification of antioxidants. Numerous in vitro methods are available which are easy to perform and largely used in screening trials. However, the results of such tests are only partly relevant for humans as certain active compounds (e.g. those with large molecular configuration) are only poorly absorbed in the gastrointestinal tract and/or may undergo metabolic degradation. Therefore experimental models are required which provide information if protective effects take place in humans under realistic conditions. Over the last years, several methods have been developed which are increasingly used in human intervention trials. The most widely used techniques are chemical determinations of oxidised guanosine in peripheral blood cells or urine and single cell gel electrophoresis (comet) assays with lymphocytes which are based on the measurement of DNA migration in an electric field. By using of DNA-restriction enzymes (formamidopyrimidine DNA glycosylase and endonuclease III) it is possible to monitor the endogenous formation of oxidised purines and pyrimidines; recently also protocols have been developed which enable to monitor alterations in the repair of oxidised DNA. Alternatively, also the frequency of micronucleated cells can be monitored with the cytokinesis block method in peripheral human blood cells before and after intervention with putative antioxidants. To obtain information on alterations of the sensitivity towards oxidative damage, the cells can be treated ex vivo with ROS (H(2)O(2) exposure, radiation). The evaluation of currently available human studies shows that in approximately half of them protective effects of dietary factors towards oxidative DNA-damage were observed. Earlier studies focused predominantly on the effects of vitamins (A, C, E) and carotenoids, more recently also the effects of fruit juices (from grapes, kiwi) and beverages (soy milk, tea, coffee), vegetables (tomato products, berries, Brussels sprouts) and other components of the human diet (coenzyme Q(10), polyunsaturated fatty acids) were investigated. On the basis of the results of these studies it was possible to identify dietary compounds which are highly active (e.g. gallic acid). At present, strong efforts are made to elucidate whether the different parameters of oxidative DNA-damage correlates with life span, cancer and other age related diseases. The new techniques are highly useful tools which provide valuable information if dietary components cause antioxidant effects in humans and can be used to identify individual protective compounds and also to develop nutritional strategies to reduce the adverse health effects of ROS.

Use of human-derived liver cell lines for the detection of environmental and dietary genotoxicants; current state of knowledge

This article gives an overview of the results of genotoxicity tests, which have been conducted within the last 5 years with the human liver cell line HepG2. It is an update of an earlier review from 1998 (by Knasmüller et al.). In addition, a number of publications are discussed which are relevant for the use of human derived liver cell lines in genetic toxicology. They concern the establishment of new endpoints, the development of new cell lines and possible pitfalls and problems. HepG2 cells have been used to test a wide variety of compounds over the last years. The most interesting observations are that the cells are highly sensitive toward polycyclic aromatic hydrocarbons and that genotoxic effects are seen with a number of carcinogenic mycotoxins, that give negative results in other in vitro assays. Carcinogenic metals such as As and Cd caused positive results as well, whereas only marginal or negative results were seen with nitrosamines. The low sensitivity toward these latter carcinogens is probably due to a lack of cytochrome P4502E1 which catalyses their activation. Also, a number of structurally different synthetic pesticides as well as bioactive plant constituents ("natural pesticides") have been tested and with some of them genotoxic effects were found. In most experiments, the formation of micronuclei was used as an endpoint; however also the single cell gel electrophoresis assay is increasingly used. Several transfectant lines of HepG2 have been constructed which express increased levels of phase I enzymes (such as CYP1A1, CYP1A2, CYP2E1 etc.); furthermore, cell lines became available which express human glutathione-S-transferases. These new clones might be particularly useful for the investigation of specific classes of genotoxicants and also for mechanistic studies. Apart from HepG2 cells, a number of other human derived liver cell lines have been isolated, but so far no data from genotoxicity experiments are available, except for Hep3B cells, which were compared with HepG2 and found to be less sensitive in general. Studies with HepG2 clones of a different origin indicate that the cells differ in regard to their sensitivity toward genotoxicants; also medium effects and the cultivation time might affect the outcome of genotoxicity studies. Overall, the results support the assumption that HepG2 cells are a suitable tool for genotoxicity testing.