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Featured researches published by Alexander Vardavas.


Drug Testing and Analysis | 2014

Rapid method for the simultaneous determination of DDTs and PCBs in hair of children by headspace solid phase microextraction and gas chromatography-mass spectrometry (HSSPME/GC-MS).

Manolis Tzatzarakis; Emmanouil G. Barbounis; Matthaios Kavvalakis; Elena Vakonaki; Elisavet Renieri; Alexander Vardavas; Aristidis M. Tsatsakis

The purpose of this study was to develop a rapid and cost efficient hair extraction method, using the headspace solid phase microextraction (HSSPME) technique for the simultaneous determination and biomonitoring of 1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane) (DDT) and its isomers/metabolites and polychlorinated biphenyls (PCBs) in hair samples. A total of 72 head hair samples were collected from children living in urban and rural regions of the island of Crete. Two hundred milligrams of hair were digested under alkaline conditions and thermostated for 30 min at 90°C while a 65 µm PDMS/DVB fibre was exposed into the headspace of the vial. Analytical parameters of the method (time of incubation, agitation speed, recovery, precision, accuracy, carry over, matrix effect, linearity, and selectivity) were examined. Recoveries of the DDTs in the spiked hair samples were calculated from 42.3% for opDDD to 87.1% for opDDE, while recoveries for PCB congeners were from 52.6% for PCB138 to 96.6 % for PCB28. The method was applied for the analysis of authentic hair samples. Significant differences (p=0.001) of the burden to total DDTs (sumDDTs) as well as of the frequencies of detection of positive samples (p=0.020) were observed between the examined regions. Moreover, significant differences in the detected concentrations of PCB congeners were observed for PCB52 (p<0.001) and PCB28 (p=0.017) as well for their prevalence between urban and rural regions. Application of HSSPME for the biomonitoring of DDTs and PCBs biomarkers in hair was tested and successfully applied to the analysis of spiked and authentic hair samples. HSSPME was found to be substantially simpler and faster procedure than previous reported sample treatment procedures.


Science of The Total Environment | 2017

Environmental metal contamination and health impact assessment in two industrial regions of Romania

Mirela Nedelescu; Daniela Luiza Baconi; Aurora Neagoe; Virgil Iordache; Miriana Stan; Paula Constantinescu; Anne-Marie Ciobanu; Alexander Vardavas; Marco Vinceti; Aristidis M. Tsatsakis

We investigated two Romanian industrial regions- Copşa Mică and Zlatna, to assess the current situation of soil pollution and bioaccumulation of Pb, Cd, Cu and Zn in different vegetable species and possible risks to consumers. Both total and mobile forms of the metals were determined in soil samples, and metal content in the edible parts of root vegetable samples was also assessed. The concentrations of Pb and Zn in soil were higher in Copşa Mică than in Zlatna (566mg/kg vs 271mg/kg for Pb and 1143mg/kg vs 368mg/kg for Zn)·The metal mobility in soil from Copsa Mica decreases in the order Zn>Cu>Cd>Pb (1.88mg/kg, 0.40mg/kg, 0.22mg/kg, 0.16mg/kg, respectively), while in Zlatna, the order was Cu>Zn>Pb>Cd (0.88mg/kg, 0.29mg/kg, 0.04mg/kg, 0.01mg/kg, respectively), apparently depending on metal and soil conditions. In Copsa Mica, the amount of Pb and Cd in vegetable samples exceeded the maximum permissible limits in carrots (median concentration 0.32mg/kg for Pb and Cd) and in yellow onions (median concentration 0.24mg/kg for Cd). In Zlatna region, the content of Cd exceeded the maximum limits in yellow onions (median concentration 0.11mg/kg). The amount of Pb was higher than the maximum acceptable level in carrots from the Zlatna region (median concentration 0.12mg/kg). Cu and Zn levels were within the normal range in all vegetable samples. In the Zlatna region, the transfer factors for Pb and Cd were higher in carrots (median values of 9.9 for Pb and 21.0 for Cd) compared to carrots harvested in Copsa Mica (median values of 4.0 for Pb and 2.0 for Cd). Daily intake rates of metals through local vegetable consumption exceeded the limit values established by the European Food Safety Authority for Pb (1.2 to 2.4 times) and Cd (5.5 to 9.1 times) in both regions, with potential adverse health effects for the local population. The results highlight the need for total soil remediation action before fruit and vegetables produced in these polluted areas can be safely consumed.


Life Sciences | 2016

Downgrading the systemic condition of rabbits after long term exposure to cypermethrin and piperonyl butoxide.

Alexander Vardavas; Persefoni Fragkiadaki; Athanasios Alegakis; Dimitrios Kouretas; Nikolaos Goutzourelas; John Tsiaoussis; Christina Tsitsimpikou; Polychronis Stivaktakis; Félix Carvalho; Aristidis M. Tsatsakis

AIM The aimof this study is to clarify the effect of cypermethrin (CY) on the oxidative stress (OS) and inflammation status of animals exposed to it and the synergistic role of piperonyl butoxide (PB0). MAIN METHODS Markers of oxidative stress, such as total antioxidant activity (TAC), protein carbonyls, hemoglobin (Hb), reduced glutathione (GSH), thiobarbituric-acid reactive substances (TBARS), along with the telomerase activity in PBMCs (peripheral blood mononuclear cells) were analyzed. KEY FINDINGS Oxidative stress markers showed statistically significant differences between groups in TAC (p b 0.001), GSH (p = 0.018) and CAT activity (p = 0.029), which depended on dose and combined effect of both compounds. Telomerase activity also showed a statistically significant difference between all groups (F = 43.48, df=6, 14, p b 0.001)with cypermethrin, piperonyl butoxide and the co-exposed groups being significantly different fromthe control group (p b 0.05). Significance: The observed results for TBARS, GSH, Hb, TAC, Crbnls and CAT from our exposed groups showed altered levels compared to control groups that could be linked to doses and combined effects of each chemical substance (cypermethrin and piperonyl butoxide). Oxidative stress markers suggest that cypermethrin, piperonyl butoxide and the co-exposed groups, induce oxidative stress as well as induction of telomerase activity.


Journal of Analytical Toxicology | 2016

Comparative Evaluation of Drug Deposition in Hair Samples Collected from Different Anatomical Body Sites

Manolis Tzatzarakis; Athanasios Alegakis; Matthaios Kavvalakis; Elena Vakonaki; Polychronis Stivaktakis; Katerina Kanaki; Alexander Vardavas; Emmanouil G. Barbounis; Aristidis M. Tsatsakis

In this study, we focused on the validation of a method for the simultaneous detection and quantification of cannabinoids, cocaine and opiates in hair as well as on the distribution of the drugs deposition in hair collected from different anatomical body sites. The proposed analytical procedure was validated for various parameters such as selectivity, linearity, limit of quantification, precision, accuracy, matrix effect and recovery. Four hundred and eighty-one samples were collected during 2010-2015 from 231 drug abusers. A 6-h ultrasonic-assisted methanolic extraction was applied for the isolation of the drugs. The analysis was performed in an liquid chromatography-mass spectrometry system for the opiates and cocaine and in a gas chromatography-mass spectrometry system for the cannabinoids. Cocaine was the most frequent detected drug (68.8-80.5%) followed by cannabinoids (47.6-63.3%) and opiates (34.7-46.7%) depending on the body site that the samples were collected. The mean concentrations of Δ9-tetrahydrocannabinol (THC) were 0.63 ± 2.11 for head, 0.54 ± 1.03 for pubic, 0.34 ± 0.51 for axillary and 0.18 ± 0.18 ng/mg for chest hair samples. The values of cocaine were 6.52 ± 15.98, 4.64 ± 10.77, 6.96 ± 38.21 and 3.94 ± 6.35 ng/mg, while the values of 6-monoacetylmorphine (MAM) were 3.33 ± 5.89, 3.06 ± 9.33, 1.37 ± 1.37 and 16.4 ± 1.77 ng/mg for head, pubic, axillary and chest samples, respectively. Differences between the detected concentrations of cocaine and opiates between the hair samples of different anatomical sites, as well as the ratio of drug metabolites to the parent compounds were observed in some cases. Statistically significant differences in the mean detected levels were noticed for morphine and heroin between head and pubic hair and also for cocaine and benzoylecgonine, between head and axillary hair samples. Moreover, the ratio of MAM to morphine and THC to cannabinol seems to correlate statistically with the total opiate or cannabinoid detected concentrations. The above differences could be attributed to several parameters associated with the structure, morphology, growth rate and other characteristics of the collected hair.


European Respiratory Journal | 2017

Respiratory irritants in e-cigarette refill liquids across nine European countries: a threat to respiratory health?

Constantine I. Vardavas; Charis Girvalaki; Alexander Vardavas; Sophia Papadakis; Manolis Tzatzarakis; Panagiotis Behrakis; Aristidis M. Tsatsakis

The rapid expansion of the e-cigarette market across European countries has raised a number of concerns within the scientific community [1, 2]. The most recent data from across the European Union revealed a substantial increase in e-cigarette experimentation, with 15% of European citizens reporting having tried e-cigarettes in 2017, representing a 7.0% increase since 2012 [3]. Annual e-cigarette sales in Europe have reached EUR 1.33 billion, and are projected to reach over EUR 10 billion by 2020 [4]. Respiratory irritants within e-cigarette refill liquids are a cause for concern for respiratory health http://ow.ly/454g30gK09m


Food and Chemical Toxicology | 2016

Long-term exposure to cypermethrin and piperonyl butoxide cause liver and kidney inflammation and induce genotoxicity in New Zealand white male rabbits.

Alexander Vardavas; Polychronis Stivaktakis; Manolis Tzatzarakis; Persefoni Fragkiadaki; Fotini Vasilaki; Maria Tzardi; Galateia Datseri; John Tsiaoussis; Athanasios Alegakis; Christina Tsitsimpikou; Valerii N. Rakitskii; Félix Carvalho; Aristidis M. Tsatsakis


Tobacco Induced Diseases | 2017

Characteristics and outcomes of e-cigarette exposure incidents reported to 10 European Poison Centers: a retrospective data analysis

Constantine I. Vardavas; Charis Girvalaki; Filippos T. Filippidis; Mare Oder; Ruth Kastanje; Irma de Vries; Lies Scholtens; Anita Annas; Silvia Plackova; Rajka Turk; Laima Gruzdyte; Fátima Rato; Dieter Genser; Helmut Schiel; Andrea Balázs; Elaine Donohoe; Alexander Vardavas; Manolis Tzatzarakis; Aristidis M. Tsatsakis; Panagiotis Behrakis


Toxicology Letters | 2018

Natural antioxidants prevent contrast-induced nephropathy by enhancing nitric oxide synthesis in an animal model

I. Fragkiadoulaki; Charalampos Mamoulakis; Athanasios Alegakis; Manolis Tzatzarakis; V. Karzi; A. Stratidakis; Elisavet Renieri; Alexander Vardavas; G. Leon; Christina Tsitsimpikou; Aristides M. Tsatsakis


Toxicology Letters | 2018

Evaluation of e-cigarette liquids on labelling, packaging and technical features prior the adoption of the Tobacco Products Directive (TPD) in multiple European countries

Manolis Tzatzarakis; Charis Girvalaki; Alexander Vardavas; Polychronis Stivaktakis; A. Nosyrev; G. Leon; Aristides M. Tsatsakis; Constantine I. Vardavas


Tobacco Prevention and Cessation | 2018

What is the content of the electronic cigarette liquids according to their flavor? An evaluation in nine European Union countries before TPD implementation

Charis Girvalaki; Manolis Tzatzarakis; Alexander Vardavas; Polychronis Stivaktakis; Christina Kyriakos; Sophia Papadakis; Aristidis M. Tsatsakis; Constantine I. Vardavas

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