George Theodorou

Dr. George Theodorou

Department of Animal Science, Agricultural University of Athens, 75 Iera Odos Str., 118 55 Athens, Greece
orcid

Research Focus & Metrics

Academic Career Length

21Years (2006-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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29 September 2006 in The Plant Cell
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TATrudie Allen
Trudie Allen
AKAthanasios Koustenis
Athanasios Koustenis
George TheodorouGeorge Theodorou
George Theodorou
DSDavid E. Somers
David E. Somers
SKSteve A. Kay
Steve A. Kay
Paul DevlinPaul Devlin
Paul Devlin
Circadian gating of light signaling limits the timing of maximum responsiveness to light to specific times of day. The fhy3 (for far-red elongated hypocotyl3) mutant of Arabidopsis thaliana is involved in independently gating signaling from a group of photoreceptors to an individual response. fhy3 shows an enhanced response to red light during seedling deetiolation. Analysis of two independent fhy3 alleles links enhanced inhibition of hypocotyl elongation in response to red light with an arrhythmic pattern of hypocotyl elongation. Both alleles also show disrupted rhythmicity of central-clock and clock-output gene expression in constant red light. fhy3 exhibits aberrant phase advances under red light pulses during the subjective day. Release-from-light experiments demonstrate clock disruption in fhy3 during the early part of the subjective day in constant red light, suggesting that FHY3 is important in gating red light signaling for clock resetting. The FHY3 gating function appears crucial in the early part of the day for the maintenance of rhythmicity under these conditions. However, unlike previously described Arabidopsis gating mutants that gate all light signaling, gating of direct red light–induced gene expression in fhy3 is unaffected. FHY3 appears to be a novel gating factor, specifically in gating red light signaling to the clock during daytime.

1 February 2018 in International Dairy Journal
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Journal Article
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EMEkaterini Moschopoulou
Ekaterini Moschopoulou
LSLambros Sakkas
Lambros Sakkas
EZEvangelia Zoidou
Evangelia Zoidou
George TheodorouGeorge Theodorou
George Theodorou
ESEleni Sgouridou
Eleni Sgouridou
Golfo MoatsouGolfo Moatsou
Golfo Moatsou

27 August 2023 in Antioxidants
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ENELENI NTALAKA
ELENI NTALAKA
IPIoannis Politis
Ioannis Politis
George TheodorouGeorge Theodorou
George Theodorou
Whey-derived peptides have been associated with different biological properties, but most peptides are usually further hydrolyzed during the digestive process. In the present study, the antioxidant capacity of 48 samples of sweet whey (SW) derived from cheeses obtained from small-scale cheese plants made with bovine, ovine, caprine or a mixture of ovine/caprine milk was assessed using both cell-free and cell-based assays. SW digestates (SW-Ds) and a fraction (<3 kDa; SW-D-P3) thereof were obtained after in vitro digestion and subsequent ultrafiltration. Antioxidant properties using four different assays were evaluated before and after digestion. Our data showed higher values (p < 0.05) for ORAC, ABTS, FRAP and P-FRAP after in vitro digestion (SW-Ds and SW-D-P3) when compared with the corresponding values before digestion. In the non-digested SW, ORAC values were higher (p < 0.05) for the bovine SW compared with all the other samples. In contrast, the ABTS assay indicated a higher antioxidant activity for the ovine SW both before digestion and for SW-D-P3 compared with the bovine SW. The fraction SW-D-P3 of the ovine SW, using HT29 cells and H2O2 as an oxidizing agent, increased (p < 0.05) the cellular antioxidant activity. Furthermore, the same fraction of the ovine/caprine mixed SW increased, through the NF-κB pathway, the expression of SOD1 and CAT, genes implicated in the oxidative response in macrophage-like THP-1 cells. These findings indicate that SW, and particularly bovine and ovine SW, could be a candidate source for physical antioxidants in human and animal nutrition.

1 December 2012 in Journal of Dairy Science
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IPIoannis Politis
Ioannis Politis
George TheodorouGeorge Theodorou
George Theodorou
ALA.D. Lampidonis
A.D. Lampidonis
AKA. Kominakis
A. Kominakis
ABA. Baldi
A. Baldi
Vitamin E supplementation, when combined with high blood α-tocopherol (>6.25 μg/mL) at dry off, has been reported to unexpectedly increased the risk for clinical mastitis in dairy cows. Furthermore, higher levels of oxidative stress in the postpartum period were related to higher risk of mastitis. The objective of the present study was to determine the relationship between various serum biomarkers of oxidative status, incidence of mastitis, and blood α-tocopherol concentrations at dry off and at calving. A total of 146 dairy cows from a commercial farm were used in an observational field study. All cows were supplemented with 3,000 and 50 IU/cow per day of all-rac-α-tocopherol during the dry period and lactation, respectively. Blood samples were collected at dry off and at calving. Serum was analyzed for α-tocopherol, levels of reactive oxygen metabolites (ROM), thiol groups (SH), and ferric-reducing ability. Three α-tocopherol groups at calving were created: high (>3 μg/mL), medium (2-3 μg/mL), and low (6.25 μg/mL), medium (4.25-6.25 μg/mL), and low (<4.25 μg/mL). All cases of clinical mastitis that occurred during the dry period and the entire subsequent lactation were verified by a veterinarian. No differences were observed in the incidence of mastitis between the 3 α-tocopherol groups based on the serum levels at dry off. Incidence of mastitis was 4 times lower in the high and medium groups when compared with the corresponding value for the low-α-tocopherol group based on the serum levels at calving. Lower levels of ROM and SH at dry off and at calving were found in the group of cows with the highest α-tocopherol values at dry off when compared with the corresponding values in the low-α-tocopherol group. The ROM values at dry off but not at calving were lower in the group of cows with the highest α-tocopherol values at calving when compared with the corresponding values in the low-α-tocopherol group. No differences were observed in ferric-reducing ability values between the 3 α-tocopherol groups at dry off or calving. No differences were observed in all biomarkers of oxidative status between healthy cows and those with mastitis. Thus, blood α-tocopherol is inversely related to certain biomarkers of oxidative stress in the postpartum period and incidence of mastitis. However, reduction in the incidence of mastitis is not mediated through a reduction in the levels of various biomarkers of oxidative stress.

18 February 2016 in Animal Production Science
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IPIrida Palamidi
Irida Palamidi
VPVasileios Paraskeuas
Vasileios Paraskeuas
RBRenata Breitsma
Renata Breitsma
GSGerd Schatzmayr
Gerd Schatzmayr
George TheodorouGeorge Theodorou
George Theodorou
KMKonstantinos Mountzouris
Konstantinos Mountzouris
The effect of dietary acidifier (AC) supplementation in combination or not with avilamycin (AV) was evaluated on broiler performance, nutrient digestibility, gizzard pH, activity of digestive enzymes and relative expression of cytokines. A 2 × 2 factorial experimental design with inclusion of AC (0 and 1 g/kg of diet) and AV (0 and 2.5 mg/kg of diet) as the main factors was implemented. Subsequently, 544-day-old male Cobb broilers were allocated in four treatments (i.e. C – no additions, AC; AV and ACAV), each having eight replicates of 17 broilers, for 6 weeks. Overall bodyweight gain (BWG) was improved (PAC = 0.035) by AC addition. BWG and feed conversion ratio were improved (P = 0.05) by AV addition in all growth periods and overall. Dry matter, organic matter digestibility and energy retention were improved by AC (PAC = 0.050, PAC = 0.045 and PAC = 0.020, respectively), or AV (PAV = 0.018, PAV = 0.013 and PAV = 0.012, respectively). In addition AV supplementation improved digestibility of ether extracts (PAV = 0.022) and crude protein (PAV = 0.042). Pancreatic trypsin activity was lower in AC (PAC = 0.027) or AV (PAV = 0.001) supplemented diets. An AC × AV effect on gizzard pH (PAC × AV = 0.034) was noted. Expression of interferon-? (PAV = 0.010), interleukin (IL) 18 (PAV = 0.048) and inducible nitric oxide synthase 2 (PAV = 0.035) in spleen were downregulated by AV. An upregulation of IL10 (PAC × AV = 0.018), IL18 (PAC × AV = 0.002) and IL22 (PAC × AV = 0.030) in the caecal tonsils was shown for the combined ACAV supplementation. In conclusion, dietary AC supplementation improved performance, nutrient digestibility and energy retention, irrespective of AV inclusion. This study has provided evidence for potential links between digestive and immune function indices with growth performance improvements.

7 January 2025 in Fermentation
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EMEirini-Maria Melanouri
Eirini-Maria Melanouri
IDIlias Diamantis
Ilias Diamantis
MDMarianna Dedousi
Marianna Dedousi
ENELENI NTALAKA
ELENI NTALAKA
PAParaskevi Antonopoulou
Paraskevi Antonopoulou
Panagiota DiamantopoulouPanagiota Diamantopoulou
Panagiota Diamantopoulou
Agricultural residues, including Pleurotus ostreatus spent mushroom substrate (SMS) and roots of (hydroponic) leafy vegetables (RLV), were tested in various proportions as substrates in new P. ostreatus cultivations, where wheat straw was the control. The impact of SMS and RLV was first evaluated by the mycelial growth rate (Kr, mm/day). Afterwards, mushroom cultivation was conducted in bags, where production characteristics like earliness (the time from substrate inoculation to first harvest) and biological efficiency (BE %, the ratio of fresh mushroom weight to dry substrate weight × 100) were examined. The study also evaluated mushroom quality, nutritional composition and bioactive content. The highest intra-cellular polysaccharide (IPS) value (50.93%, w/w) was observed in the substrate containing SMS 90%, while combining SMS with RLV resulted in higher IPS values compared to mixtures that also included wheat bran (WB) and soybean flour (SF). Furthermore, the use of RLV reduced the fat content compared to the control substrate, except in the case of the SMS 50%–RLV 40% substrate, where the highest fat content was observed in the produced mushrooms (4.68% w/w). Additionally, the protein content increased with the use of RLV. The highest triterpene content was found in the SMS 90%–RLV 10% (11.52 ursolic acid mg/g d.w.). However, the control substrate exhibited the fastest Kr (6.5 mm/d), as well as the highest BE (87.8%) and total phenolic compound value (30.31 mg GAE/g d.w.). Significant antioxidant activity was observed in all extracts, while the total flavonoid content was low. Glucose was the dominant monosaccharide (over 51.5%, w/w), and linoleic acid (18:2; over 57.05%, w/w) was the primary fatty acid across all mushrooms. This study also enhances our knowledge by which SMS and RLV influence the NFE2L2/HMOX-1 molecular pathway, thereby affecting specific antioxidant-related genes. These effects were observed through the impact of P. ostreatus protein and carbohydrate extracts on LPS-challenged THP-1-derived macrophages. A positive impact on the gene expression of HMOX1, CAT and NFE2L2 during incubation with the aforementioned samples was observed. These findings support the sustainable use of agricultural by-products in mushroom cultivation, offering an environmentally friendly approach while producing valuable products like mushrooms.