Department of Medical Laboratories, Faculty of Health and Caring Professions, Technological Educational Institute (TEI) of Athens, Greece.
karikasg@teiath.gr
George-Albert Karikas Professor
Born in Piraeus, Greece, and married with a son.
He holds a bachelor's degree in Pharmaceutical Sciences, from the National and Kapodistrian University of Athens, Greece(1976).
He was awarded a Doctorate in Biochemistry, from the Faculty of Natural Sciences, National and Kapodistrian University of Athens, Greece (1981).
Earned his Ph.D (Chemistry of natural products) from Manchester University, England, U.K. (1986).
He has been working as biochemist in the Research Biochemical Laboratory, "Alexandra" Hospital, Medical School, University of Athens (1977-1981), and as Director of the National Health System, in Parenteral Nutrition and Pharmacokinetics Unit, Children’s Hospital “Aghia Sophia”, Athens, and in the General Hospital “Tzaneio”, Piraeus, Greece (1989-2007).
From 1982, he also worked and taught as visiting research fellow and professor, in Manchester University, England, Salamanca University, Spain, University of Erlangen-Nuremberg, Germany, National University of Panama, Orebro University, Sweden, Athens University, Greece, Research Institute of Child Health, Greece, TEI of Athens, Greece.
He has published over 60 original research papers, chapters, reviews and monographies in international peer journals, along with numerus papers and posters presented in Greek and International Congresses.
His research interests are within the spectrum of Biochemistry-Clinical Chemistry, including studies on:
1. Enzymatic and antioxidant systems in relation to metabolic, cardiovascular and nutritional biomarkers 2. DNA molecular interactions and pharmacokinetic measurements 3. Biochemical analysis and structure elucidation of bioactive natural products.
His academic work has obtained more than 600 citations, scholarships and awards.
Editor of books for students on Biochemistry, Practical Biochemistry and Pharmacology.
Regular referee in a number of international scientific journals such:
Metabolism, European Journal of Clinical Investigation, Pharmaceutical Biology, International Journal of Medicine and Medical Sciences, Clinical Reviews and Opinions, Journal of Medical Laboratory and Diagnosis, Journal of Cancer Research and Experimental Oncology, The Protein Journal, Investigational New Drugs, Recent Patents on Anticancer Drug Discovery, Mini Reviews in Medicinal Chemistry.
Member of : New York Academy of Sciences, American Association for the Advancement of Science (AAAS), European Society of Clinical Pharmacy, Balkan Union of Oncology, Hellenic Biochemical Biophysical Society, Hellenic Society of Clinical Chemistry-Clinical Biochemistry, Phytochemical Society of Europe, Scientific Conference and Hospital Boards, etc.
Currently,professor, teaching Biochemistry, Clinical Chemistry and Pharmacokinetics.
Head of the Department of Medical Laboratories, TEI of Athens, Greece, and Erasmus LLP Academic Coordinator (2010-).
Abstract: Natural products have afforded a rich source of compounds that have found many applications in cancer chemotherapy. Furthermore, the vast structural spectrum of natural compounds can provide "lead compounds" for therapeutic improvement by molecular modification. Over 70% of anticancer compounds are either natural products, or natural product-derived substances. On the other hand conjugation of toxic natural products to monoclonal antibodies or polymeric carriers can lead to more efficacious targeted therapies. Since less than 15% of higher plants have been systematically investigated, the natural products research towards chemotherapy requires further attention and multi-scientific collaboration. An enforcing application to chemotherapy, using natural products, is also chemoprevention. Apart from vegetables and fruit, more than 1,000 different phytochemicals are already proved to possess interesting chemopreventing activities. Effectiveness of chemopreventing agents reflects their ability to counteract certain upstream signals that leads to genotoxic damage, redox imbalances and other forms of cellular stress. Chemoprevention by edible phytochemicals is now considered to be an inexpensive, readily applicable, acceptable and accessible approach to cancer control and management. The present short review deals with a number of recent biochemical and therapeutic routes, concerning current approaches towards natural anticancer agents in clinical practice, new candidate oncotherapy drugs from plants, marine and microorganisms, as well as promising chemopreventing agents from nature.
Abstract: To investigate PON 1/Aryl activities in basketball players with or without alpha-T supplementation pre- and post-training. Vitamin E (alpha-tocopherol, alpha-T) reduces lipid peroxidation. Paraoxonase 1/arylesterase (PON 1/Aryl) activities are closely related to oxidation and atherogenesis.
Abstract: To investigate the effect of the mode of delivery on maternal-neonatal amino acid levels as high blood levels of some amino acids are implicated with endurance exercise.
Abstract: Biogenic amine, adrenaline, noradrenaline, dopamine and 5-hydroxy-tryptamine (5-HT) levels are related to interleukin-6 (IL-6) plasma concentrations and endurance exercise. The aim of our study was to investigate the effect of the mode of delivery on maternal-neonatal IL-6, biogenic amine and their precursor amino acid levels.
Abstract: To investigate the effects of diet on the antiatherogenic enzyme Paraoxonase 1/Arylesterase (PON1/Aryl) activities in patients with disorders of galactose metabolism.
Abstract: We evaluated the serum levels of lipids, lipoproteins, apolipoproteins, along with a number of minerals and trace elements such as Ca, Mg, Cu and Zn in a group of children after 6 months of valproic acid monotherapy. Thirty patients with seizures, mean age, 9.8+/-2.6 years and 79 healthy children (controls), mean age, 10.9+/-3.2 years, formed the two styd groups. The patient group was treated with valproic acid (27.9+/-14.8 mg/kg/24 hr). Patients underwent clinical and laboratory evaluations including liver function tests, NH3, lipid, mineral and selected trace element levels before and after six months on valproic acid treatment, whereas controls only one evaluation. Liver function data and NH3 levels were found to be elevated in the group of patients, whereas albumin level was reduced. Triglycerides, total cholesterol, HDL-C, apolipoprotein (ApoA)-1, Apo B and Ca concentrations were found relative to control values, LDL-C, VLDL-C, Mg, Cu, Zn, were measured significantly altered (P<0.0001) compared to controls. The ratios ApoA-1/ApoB, HDL-C/ApoA-1, LDL-C/Apo B, which were closely related to the size of LDL particles, where correlated with Zn/Cu (P<0.001). Serum lipid profile, especially LDL size, indirectly evaluated for the first time and metal levels were found to be significantly changed, after six months on valproic acid monotherapy, suggesting a possible risk of developing coronary heart disease. Since valproic acid is a long-term treatment, it could be recommended that the incorporation of measurements of lipids, lipoproteins, apolipoproteins and trace elements in the "follow up" laboratory testing could be a preventive measure.
Abstract: Over the past decade, it has been well established that elevated total serum homocysteine (tHcy) in adults is associated with increased risk of cardiovascular and thromboembolic diseases. Since risk factors for such diseases are established at a young age, the aim of the present study was to measure serum tHcy levels in 134 (71 boys, 63 girls) randomly selected healthy preschool children aged 4-6 years (mean 5.1), and to investigate possible correlation with paraoxonase 1 (PON1) activity, an antioxidant enzyme that contributes to the antiatherogenic properties of high-density lipoprotein (HDL).
Abstract: Valproic acid (VPA) and 8-hydroxy-2-deoxyguanosine (8-OHdG) are implicated with the free radicals production. We aimed to evaluate total oxidant status (TOS) and 8-OHdG in children on VPA monotherapy. Fifty patients with seizures, mean age 8.5+/-3.6 years, were divided into group A (N=26) and group B (N=24) with VPA serum levels 81.0+/-8.0 and 114+/-9.7 microg/mL, respectively. Thirty healthy children were the controls. Liver function tests and lipids were determined with routine methods, TOS and 8-OHdG with commercial kits, after 60 days on VPA therapy. Liver function parameters, lipids, TOS (647+/-43 micromol/L) and 8-OHdG (0.49+/-0.08 ng/mL) were significantly higher in group B than those in group A (580+/-40 micromol/L, 0.37+/-0.04 ng/mL, p<0.001) and controls (124+/-30 micromol/L, 0.11+/-0.04 ng/mL, p<0.001, respectively). Significant correlation coefficients were found between 8-OHdG versus TOS (r=0.67, p<0.001) and 8-OHdG versus VPA (r=0.60, p<0.001) levels. It is suggested that VPA impairs the liver function resulting in free radicals production. The latter seems to produce DNA oxidative damage in liver cells, not excluding neuronal cells, as evidenced by the measured remarkably increased 8-OHdG serum levels. 8-OHdG evaluation may be a useful biomarker to follow up the increased risk of degeneration process in VPA patients.
Abstract: Patients with phenylketonuria (PKU) have a diet-controlled deficiency in the conversion of phenylalanine (Phe) to tyrosine (Tyr), leading to decreased production of noradrenaline, adrenaline, and dopamine. Poor diet control results in high plasma Phe and low plasma Tyr and catecholamine concentrations. Ghrelin, a recently described gastrointestinal hormone that is elevated in the fasting state and low in the fed state, is considered a major appetite-stimulating hormone, possibly involved in the generation of obesity and insulin resistance. We evaluated morning preprandial plasma ghrelin levels in 14 diet-controlled and 15 poorly controlled PKU patients and 20 age- and body mass index (BMI)-matched healthy children (controls) and correlated its concentrations with those of Phe and catecholamines as well as with their BMI and 24-h nutrient intake. Plasma ghrelin levels were measured by RIA, plasma catecholamine concentrations were determined by HPLC with electrochemical detection, and Phe and Tyr levels were measured in an amino acid analyzer. The ghrelin concentration (744 +/- 25 ng/liter) in diet-controlled patients did not differ from that in controls (802 +/- 26 ng/liter; P > 0.05). On the contrary, the ghrelin concentration was significantly reduced in poorly controlled patients (353 +/- 23 ng/liter; P < 0.0001). Ghrelin correlated negatively with Phe in all three groups, whereas it correlated positively with catecholamine levels and energy intake and negatively with BMI only in diet-controlled patients and controls. We conclude that ghrelin secretion may receive positive direct or indirect input from catecholamines. The absence of a correlation between ghrelin and catecholamines, energy intake, or BMI in PKU patients on an inadequate diet may be due to dysregulation of their neuroendocrine system and might be affected by high Phe levels in the stomach and/or central nervous system.
Abstract: Classical phenylketonuria (PKU) is an inborn error of metabolism characterized by high Phenylalanine (Phe) levels in blood and treated with a special low Phe diet which can be defined as "nonatherogenic". Since coronary heart disease (CHD) was reported to be a disease of zinc and copper imbalance, we aimed indirectly to evaluate the effect of the special diet on the size of LDL particles and to investigate whether some minerals and trace elements are involved in their lipoprotein metabolism.
Abstract: Low folate and vitamin B(12) concentrations during pregnancy are implicated with neural tube defects (NTD) and neurological manifestations in the neonates.
Abstract: Better dosing is needed for antibiotics, including teicoplanin (TEI), to prevent emergence of resistant bacterial strains. Here, we assess the TEI pharmacokinetics (PK) related to a 10 mg/l minimum inhibitory concentration (MIC) target in ICU children (4 to 120 months; n = 20) with gram+ infections.
Abstract: Phenylketonuria (PKU), an inborn error of phenylalanine (Phe) metabolism, is treated with a low Phe lifelong diet, which is a vegetarian and contains many antioxidants.
Abstract: Jaundice is one of the most common and one of the vexing problems that can occur in newborns. A newborn screening test for biotinidase deficiency has been added to many national screening programmes.
Abstract: The aim of this study was to investigate the known risk factors, such as lipids, homocysteine and endothelin, for the development of coronary artery disease (CAD) in phenylketonuria (PKU) patients, depending on their diet. The PKU patients (n = 74) were divided into two groups. Group A (n = 34; mean age 6.78 +/- 1.5 y) adhered strictly to a diet and group B (n = 40; mean age 8.0 +/- 3.2 y) did not comply with the diet. The control group comprised 50 healthy non-PKU children. All groups were evaluated for blood levels of homocysteine and vitamin B6 by high-performance liquid chromatography, vitamin B12 and folate in serum by a radioassay, lipids by a routine method, and lipoprotein(a) and endothelin-1 with an immunoassay. Homocysteine levels (28.65 +/- 3.3 micromol l(-1)) were increased in group A compared with group B (6.86 +/- 1.6 micromol l(-1)) and the controls (6.9 +/- 2.0 micromol l(-1)) (p < 0.001). Vitamin B6 (10.7 +/- 10.9 nmol l(-1)), vitamin B12 (98.5 +/- 22.3 pmol l(-1)), folate (2.35 +/- 1.3 nmol l(-1)) and lipids were decreased in group A. The other vascular risk factors, which were not dependent on diet [lipoprotein(a) and endothelin-1], did not differ among the three groups. Conclusion: PKU patients on a strict diet had low vitamin B6, vitamin B12 and folate levels resulting in moderate hyperhomocysteinaemia. The evaluation of these vitamins at short intervals and their supplementation could be an early measure in the prevention of CAD.
Abstract: To evaluate the activities of Na+,K+-ATPase and Mg2+-ATPase in erythrocyte membranes from phenylketonuric (PKU) patients and to correlate the enzyme activities with their blood phenylalanine (Phe) levels, biogenic amines as well as with their precursors tyrosine (Tyr) and tryptophan (Try).
Abstract: a) To evaluate acetylcholinesterase (AChE) activities in erythrocyte membranes from phenylketonuric (PKU) patients and controls and to correlate with their plasma phenylalanine (Phe), tyrosine (Tyr), alanine (Ala) and dopamine (DA) levels. b) To determine the in vitro effects of Phe, Ala and Phe plus Ala on their AChE activities.
Abstract: This study aimed to provide associations of age and gender with serum lipoprotein(a) [Lp(a)] levels and percentile distribution data for Greek children. In total, 3298 children (1590M, 1708F, aged 6-14 y) participated in the study. Lp(a) levels were evaluated with an immunosorbent assay. Mean Lp(a) levels were 153-157 mg l(-1) for boys and 146-151 mg l(-1) for girls, and median levels 133-139 mg l(-1) for boys and 100-108 mg l(-1) for girls. Conclusion: The Lp(a) levels in these children were the lower ever reported. These results suggest that the young Greek population is not at high risk of developing coronary heart disease as a result of high Lp(a) levels.
Abstract: Valproic acid (VPA) is an effective antiepileptic drug (AED), which is associated with dose-related adverse reactions such as skin rash, hair loss (alopecia), etc. Profound as well as partial biotinidase deficiency causes dermatologic manifestations similar these. Therefore, it was of interest to evaluate serum biotinidase activity in patients receiving VPA monotherapy.
Abstract: The use of Isotretinoin (Iso) for cystic acne (CA) therapy includes marked side-effects such as dyslipidemia, increased liver enzymes, and reduction of biotinidase activity. Moreover, Homocysteine (Hcy), an amino acid, is metabolized in the liver requiring folate, vitamin B6, vitamin B12, and the activity of enzymes, i.e. cystathionine-beta-synthase. Increased blood levels of Hcy are associated with premature occlusive vascular disease.
Abstract: Among the reaction and effects of isotretinoin, mucocutaneous reactions, xerosis and erythema of the skin as well as elevation of liver enzymes and lipids except high density lipoprotein have been reported.
Abstract: To elucidate associations of age and sex with serum cholesterol and triglyceride levels and to provide for the first time percentile distribution data for pediatric lipids.
Abstract: Acetylcholinesterase (AChE) is a significant component of the membrane contributing to the permeability changes during synaptic transmission and conduction. Phenylketonuria is a group of metabolic disorders in which phenylalanine (Phe) is highly elevated in blood (up to 0.1 M) resulting in mental retardation etc. AChE activity was measured spectrophotometrically after incubation with various Phe concentrations. Phe interaction with DNA was evaluated with an established HPLC method. Phe was found to inhibit AChE almost 40%, at a concentration of 5 mM, whereas a 62.5% DNA peak exclusion (molecular interaction) was observed when Phe was incubated with DNA at a concentration of 3 mM. In addition the ratio of DNA: Phe determined the potency of the observed molecular effect.
Abstract: The most significant effect, observed in the preliminary pharmacological evaluation of the whole ethanol extract and the alkaloidal fraction of Cephäelis axillaris, was the hyperemia of ears and external mucosas which was most probably due to an alpha-adrenergic blocking activity. In addition, both samples also induced a marked hypotension in normotensive as well as hypertensive (SHR) rats and inhibited the increases of blood pressure induced by i.v. administration of noradrenaline in pithed rats. The structures of the major alkaloidal components of the extract were elucidated on the basis of chemical characterization assays and IR, UV, 1H and 13C one and two-dimensional NMR analyses.
