Molecularly imprinted polymers can be anticipated as synthetic imitation of natural antibodies, r... more Molecularly imprinted polymers can be anticipated as synthetic imitation of natural antibodies, receptors and enzymes. In case of successful imprinting the selectivity and affinity of the imprint for substrate molecules are comparable with those of natural counterparts. The selection of the optimal functional monomer, monomer/template ratio as well as choosing of polymerization solvent is crucial determinants of the successful imprinting. In the present study the simulation approach to the development of molecular imprinting polymers for the extraction of new protein kinase ATP-competitive inhibitors is presented. By imprinting tri-O-acetyladenosine into polymer matrix the synthetic reproduction of adenosine triphosphate binding site to protein kinases can be fabricated and further used for adenosine triphosphate analogs screening in different sources. The optimized geometrical structure and energy of the pre-polymerization complexes of tri-Oacetyladenosine (template) with three different monomersmethacrylic acid, 3-vinyl benzoic acid and acrylamide in vacuum were calculated using hybrid quantum mechanical/molecular mechanical (QM/MM) approach. These calculations demonstrate that methacrylic acid forms the most stable complex with template, the next is 3-vinyl benzoic acid complex and the thirdacrylamide one. The bond energies of the complexes are shown to increase monotonically as more monomers are linked to the template. The same conclusions are made from purely quantum selfconsistent field calculations of pre-polymerization complex energy and structure. Hybrid calculation is shown to be effective and can substantially accelerate the development of the imprinting technology.
In this study, exposure levels of organochlorine pesticides (OCs) were determined in general popu... more In this study, exposure levels of organochlorine pesticides (OCs) were determined in general population residing in Larissa, central Greece. Serum samples from 103 volunteers were analyzed by optimized headspace solid-phase microextraction gas chromatography-mass spectrometry, to detect and quantify OC levels. The most frequently detected analytes were p,p'-DDE (frequency 99%, median:1.25ng/ml) and Hexachlorobenzene (HCB) (frequency 69%, median: 0.13ng/ml). Statistical analysis revealed a significant relationship of p,p'-DDE and HCB levels with age.
Cardiac complications are common in carbon monoxide (CO) poisoning and associated with high morbi... more Cardiac complications are common in carbon monoxide (CO) poisoning and associated with high morbidity and mortality. We have previously shown that erythropoietin (EPO) could reduce CO-induced cardiac ischemia in rat. In the current study, the anti-apoptotic effect of EPO during CO cardiotoxicity was investigated in order to elucidate the mechanism of EPO anti-ischemic action. Wistar rats were exposed to CO (250, 1000 and 3000ppm). EPO (5000IU/kg) was administered to all groups by intraperitoneal injection at the end of CO exposure period. TUNEL and caspase-3 activity levels were assessed to investigate the effects of CO exposure and subsequent EPO administration on myocardial apoptosis. The changes of mitochondrial membrane potential (MMP) were also assessed with sensitive lipophilic dye JC-1 by flow cytometry. The roles of Bcl2 and Bax in EPO protective effect were investigated by Western blotting. Myocardial apoptosis was observed following CO exposure. Moreover, mitochondrial mem...
Nine human acute poisonings due to intentional ingestion of organophosphorous pesticides are pres... more Nine human acute poisonings due to intentional ingestion of organophosphorous pesticides are presented. Six of the victims died. Six patients were treated in the Intensive Care Unit (ICU) from 34 h to 45 d, while 3 were found dead by relatives. Two of the patients treated in the ICU fully recovered after 15 and 24 d while the third survivor developed delayed neuropathy. Organophosphate blood levels were determined on admission and during therapy, and in 1 case atropine and pralidoxime levels were also detected. Significant fluctuations of the plasma cholinesterase activity were observed during therapy. Postmortem analysis revealed higher levels of pesticides in organs (eg 23.1 micrograms fenthion/g kidney) and in fat (135.2 micrograms fenthion/g) than in blood (eg 4.8 micrograms fenthion/ml) and vitreous humor. Considerable pesticide was measured in testis (eg 5.8 micrograms fenthion/g, 0.8 micrograms methidathion/g) and uterus (170.5 micrograms malathion/g). Extracorporeal decontamination to enhance pesticide elimination is a therapeutic challenge.
The relatively recent recognition of widespread vitamin D deficiency in general population and as... more The relatively recent recognition of widespread vitamin D deficiency in general population and as well revealing of its new roles in human health and disease have increased exponentially the request in vitamin D status evaluation in patients. The concentration of vitamin D primary metabolites 25-hydroxyvitamin D3/D2 in plasma/serum is accepted as reliable index of vitamin D status. The direct LC based analytical approaches due to their specificity and selectivity are recognized as most reliable, “gold standard”, for quantification of 25-OH D3/D2. However in clinical practice more often indirect (protein) binding assays are used in spite of their recognized drawbacks and deteriorations. This can be attributed mainly to timeconsuming, labor and cost intensive sample pre-treatment prerequisite in LC based approaches. The automatic, on-line sample treatment can abrogate this limitation and here we present the UHPLC-on-line SPE method for the quantification of 25-OH D3/D2 in plasma/serum...
Bulletin of the Academy of Sciences of the USSR Division of Chemical Science, 1983
It was shown by us [1] that the reaction of 3,6-di-tert-butyl-o-benzoquinone (Q) with SiF 4 leads... more It was shown by us [1] that the reaction of 3,6-di-tert-butyl-o-benzoquinone (Q) with SiF 4 leads to the osemiquinolate complex (I) 1t + s~4~(~ si~3 (~) (~> = 3,6-di-tert-butylpyrocatechol ligand, R = t-Bu.
Consumers prefer organic food as they consider it healthier and safer. Since Aflatoxin M1 (AFM1) ... more Consumers prefer organic food as they consider it healthier and safer. Since Aflatoxin M1 (AFM1) in milk and dairy is considered as hazard to human health this study aimed to assess the level of AFM1 contamination in ewes and goats raw milk in Greece, identify possible risk factors and compare organic and conventional milk.
CYP1A2 is important for metabolizing various clinically used drugs. Phenotyping of CYP1A2 may pro... more CYP1A2 is important for metabolizing various clinically used drugs. Phenotyping of CYP1A2 may prove helpful for drug individualization therapy. Several HPLC methods have been developed for quantification of caffeine metabolites in plasma and urine. Aim of the present study was to develop a valid and simple HPLC method for evaluating CYP1A2 activity during exposure in xenobiotics by the use of human saliva. Caffeine and paraxanthine were isolated from saliva by liquid-liquid extraction (chlorophorm/isopropanol 85/15v/v). Extracts were analyzed by reversed-phase HPLC on a C18 column with mobile phase 0.1% acetic acid/methanol/acetonitrile (80/20/2 v/v) and detected at 273nm. Caffeine and paraxanthine elution times were <13min with no interferences from impurities or caffeine metabolites. Detector response was linear (0.10-8.00µg/ml, R(2) >0.99), recovery was >93% and bias <4.47%. Intra- and inter-day precision was <5.14% (n=6). The limit of quantitation was 0.10µg/ml an...
Bulletin of the Academy of Sciences of the USSR Division of Chemical Science, 1990
eva T0 I. Prokof'eva, A. I. Prokof'ev, and V. V. Ershov UDC 542.97:543.422.27:547.567 Tetrafluoro... more eva T0 I. Prokof'eva, A. I. Prokof'ev, and V. V. Ershov UDC 542.97:543.422.27:547.567 Tetrafluorosilane-catalyzed redox reactions of 3,6-di-tert-butyl-ortho-benzoquinone have been examined. From the EPR spectroscopic data and a study of the reaction products, a mechanism for these reactions is proposed involving the formation of a quinone--tetrafluorosilane complex which has strong oxidizing properties, and which enables the original quinone to undergo further reactions.
Bulletin of the Academy of Sciences of the USSR Division of Chemical Science, 1986
17.75 MHz (29Si) for sealed, evacuated 10% solutions of (I) in CDCI 3-CCI 4-CD2CI 2 relative to T... more 17.75 MHz (29Si) for sealed, evacuated 10% solutions of (I) in CDCI 3-CCI 4-CD2CI 2 relative to TMS. The 29Si NMR measurements were carried out using the INEPT method.
Molecularly imprinted polymers can be anticipated as synthetic imitation of natural antibodies, r... more Molecularly imprinted polymers can be anticipated as synthetic imitation of natural antibodies, receptors and enzymes. In case of successful imprinting the selectivity and affinity of the imprint for substrate molecules are comparable with those of natural counterparts. The selection of the optimal functional monomer, monomer/template ratio as well as choosing of polymerization solvent is crucial determinants of the successful imprinting. In the present study the simulation approach to the development of molecular imprinting polymers for the extraction of new protein kinase ATP-competitive inhibitors is presented. By imprinting tri-O-acetyladenosine into polymer matrix the synthetic reproduction of adenosine triphosphate binding site to protein kinases can be fabricated and further used for adenosine triphosphate analogs screening in different sources. The optimized geometrical structure and energy of the pre-polymerization complexes of tri-Oacetyladenosine (template) with three different monomersmethacrylic acid, 3-vinyl benzoic acid and acrylamide in vacuum were calculated using hybrid quantum mechanical/molecular mechanical (QM/MM) approach. These calculations demonstrate that methacrylic acid forms the most stable complex with template, the next is 3-vinyl benzoic acid complex and the thirdacrylamide one. The bond energies of the complexes are shown to increase monotonically as more monomers are linked to the template. The same conclusions are made from purely quantum selfconsistent field calculations of pre-polymerization complex energy and structure. Hybrid calculation is shown to be effective and can substantially accelerate the development of the imprinting technology.
In this study, exposure levels of organochlorine pesticides (OCs) were determined in general popu... more In this study, exposure levels of organochlorine pesticides (OCs) were determined in general population residing in Larissa, central Greece. Serum samples from 103 volunteers were analyzed by optimized headspace solid-phase microextraction gas chromatography-mass spectrometry, to detect and quantify OC levels. The most frequently detected analytes were p,p'-DDE (frequency 99%, median:1.25ng/ml) and Hexachlorobenzene (HCB) (frequency 69%, median: 0.13ng/ml). Statistical analysis revealed a significant relationship of p,p'-DDE and HCB levels with age.
Cardiac complications are common in carbon monoxide (CO) poisoning and associated with high morbi... more Cardiac complications are common in carbon monoxide (CO) poisoning and associated with high morbidity and mortality. We have previously shown that erythropoietin (EPO) could reduce CO-induced cardiac ischemia in rat. In the current study, the anti-apoptotic effect of EPO during CO cardiotoxicity was investigated in order to elucidate the mechanism of EPO anti-ischemic action. Wistar rats were exposed to CO (250, 1000 and 3000ppm). EPO (5000IU/kg) was administered to all groups by intraperitoneal injection at the end of CO exposure period. TUNEL and caspase-3 activity levels were assessed to investigate the effects of CO exposure and subsequent EPO administration on myocardial apoptosis. The changes of mitochondrial membrane potential (MMP) were also assessed with sensitive lipophilic dye JC-1 by flow cytometry. The roles of Bcl2 and Bax in EPO protective effect were investigated by Western blotting. Myocardial apoptosis was observed following CO exposure. Moreover, mitochondrial mem...
Nine human acute poisonings due to intentional ingestion of organophosphorous pesticides are pres... more Nine human acute poisonings due to intentional ingestion of organophosphorous pesticides are presented. Six of the victims died. Six patients were treated in the Intensive Care Unit (ICU) from 34 h to 45 d, while 3 were found dead by relatives. Two of the patients treated in the ICU fully recovered after 15 and 24 d while the third survivor developed delayed neuropathy. Organophosphate blood levels were determined on admission and during therapy, and in 1 case atropine and pralidoxime levels were also detected. Significant fluctuations of the plasma cholinesterase activity were observed during therapy. Postmortem analysis revealed higher levels of pesticides in organs (eg 23.1 micrograms fenthion/g kidney) and in fat (135.2 micrograms fenthion/g) than in blood (eg 4.8 micrograms fenthion/ml) and vitreous humor. Considerable pesticide was measured in testis (eg 5.8 micrograms fenthion/g, 0.8 micrograms methidathion/g) and uterus (170.5 micrograms malathion/g). Extracorporeal decontamination to enhance pesticide elimination is a therapeutic challenge.
The relatively recent recognition of widespread vitamin D deficiency in general population and as... more The relatively recent recognition of widespread vitamin D deficiency in general population and as well revealing of its new roles in human health and disease have increased exponentially the request in vitamin D status evaluation in patients. The concentration of vitamin D primary metabolites 25-hydroxyvitamin D3/D2 in plasma/serum is accepted as reliable index of vitamin D status. The direct LC based analytical approaches due to their specificity and selectivity are recognized as most reliable, “gold standard”, for quantification of 25-OH D3/D2. However in clinical practice more often indirect (protein) binding assays are used in spite of their recognized drawbacks and deteriorations. This can be attributed mainly to timeconsuming, labor and cost intensive sample pre-treatment prerequisite in LC based approaches. The automatic, on-line sample treatment can abrogate this limitation and here we present the UHPLC-on-line SPE method for the quantification of 25-OH D3/D2 in plasma/serum...
Bulletin of the Academy of Sciences of the USSR Division of Chemical Science, 1983
It was shown by us [1] that the reaction of 3,6-di-tert-butyl-o-benzoquinone (Q) with SiF 4 leads... more It was shown by us [1] that the reaction of 3,6-di-tert-butyl-o-benzoquinone (Q) with SiF 4 leads to the osemiquinolate complex (I) 1t + s~4~(~ si~3 (~) (~> = 3,6-di-tert-butylpyrocatechol ligand, R = t-Bu.
Consumers prefer organic food as they consider it healthier and safer. Since Aflatoxin M1 (AFM1) ... more Consumers prefer organic food as they consider it healthier and safer. Since Aflatoxin M1 (AFM1) in milk and dairy is considered as hazard to human health this study aimed to assess the level of AFM1 contamination in ewes and goats raw milk in Greece, identify possible risk factors and compare organic and conventional milk.
CYP1A2 is important for metabolizing various clinically used drugs. Phenotyping of CYP1A2 may pro... more CYP1A2 is important for metabolizing various clinically used drugs. Phenotyping of CYP1A2 may prove helpful for drug individualization therapy. Several HPLC methods have been developed for quantification of caffeine metabolites in plasma and urine. Aim of the present study was to develop a valid and simple HPLC method for evaluating CYP1A2 activity during exposure in xenobiotics by the use of human saliva. Caffeine and paraxanthine were isolated from saliva by liquid-liquid extraction (chlorophorm/isopropanol 85/15v/v). Extracts were analyzed by reversed-phase HPLC on a C18 column with mobile phase 0.1% acetic acid/methanol/acetonitrile (80/20/2 v/v) and detected at 273nm. Caffeine and paraxanthine elution times were <13min with no interferences from impurities or caffeine metabolites. Detector response was linear (0.10-8.00µg/ml, R(2) >0.99), recovery was >93% and bias <4.47%. Intra- and inter-day precision was <5.14% (n=6). The limit of quantitation was 0.10µg/ml an...
Bulletin of the Academy of Sciences of the USSR Division of Chemical Science, 1990
eva T0 I. Prokof'eva, A. I. Prokof'ev, and V. V. Ershov UDC 542.97:543.422.27:547.567 Tetrafluoro... more eva T0 I. Prokof'eva, A. I. Prokof'ev, and V. V. Ershov UDC 542.97:543.422.27:547.567 Tetrafluorosilane-catalyzed redox reactions of 3,6-di-tert-butyl-ortho-benzoquinone have been examined. From the EPR spectroscopic data and a study of the reaction products, a mechanism for these reactions is proposed involving the formation of a quinone--tetrafluorosilane complex which has strong oxidizing properties, and which enables the original quinone to undergo further reactions.
Bulletin of the Academy of Sciences of the USSR Division of Chemical Science, 1986
17.75 MHz (29Si) for sealed, evacuated 10% solutions of (I) in CDCI 3-CCI 4-CD2CI 2 relative to T... more 17.75 MHz (29Si) for sealed, evacuated 10% solutions of (I) in CDCI 3-CCI 4-CD2CI 2 relative to TMS. The 29Si NMR measurements were carried out using the INEPT method.
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Papers by Andreas Tsakalof