Constantin Tamvakopoulos

Dr. Constantin Tamvakopoulos

Pharmacology & Pharmacotechnology, Biomedical Research Foundation of the Academy of Athens, 4 Soranou Ephessiou Street, 11527 Athens, Greece

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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15 February 2007 in Clinical Cancer Research
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CTConstantin Tamvakopoulos
Constantin Tamvakopoulos
KDKonstantinos Dimas
Konstantinos Dimas
ZSZacharias D. Sofianos
Zacharias D. Sofianos
Sophia HatziantoniouSophia Hatziantoniou
Sophia Hatziantoniou
ZHZhiyong Han
Zhiyong Han
PPPanayotis Pantazis
Panayotis Pantazis
Purpose: The plant-derived compound curcumin has shown promising abilities as a cancer chemoprevention and chemotherapy agent in vitro and in vivo but exhibits poor bioavailability. Therefore, there is a need to investigate modified curcumin congeners for improved anticancer activity and pharmacokinetic properties. Experimental Design: The synthetic curcumin analogue dimethoxycurcumin was compared with curcumin for ability to inhibit proliferation and apoptosis of human HCT116 colon cancer cells in vitro by estimating the GI50 and LC50 values and detecting the extent of apoptosis by flow cytometry analysis of the cell cycle. Metabolic stability and/or identification of metabolites were evaluated by recently developed mass spectrometric approaches after incubation with mouse and human liver microsomes and cancer cells in vitro. Additionally, circulating levels of dimethoxycurcumin and curcumin were determined in mice following i.p. administration. Results: Dimethoxycurcumin is significantly more potent than curcumin in inhibiting proliferation and inducing apoptosis in HCT116 cells treated for 48 h. Nearly 100% of curcumin but <30% of dimethoxycurcumin was degraded in cells treated for 48 h, and incubation with liver microsomes confirmed the limited metabolism of dimethoxycurcumin. Both compounds were rapidly degraded in vivo but dimethoxycurcumin was more stable. Conclusions: Compared with curcumin, dimethoxycurcumin is (a) more stable in cultured cells, (b) more potent in the ability to kill cancer cells by apoptosis, (c) less extensively metabolized in microsomal systems, and (d) more stable in vivo. It is likely that the differential extent of apoptosis induced by curcumin and dimethoxycurcumin in vitro is associated with the metabolite profiling and/or the extent of stability.

22 November 2013 in CardioVascular and Interventional Radiology
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KMKATERINA MALAGARI
KATERINA MALAGARI
MPMaria Pomoni
Maria Pomoni
HMHippocrates Moschouris
Hippocrates Moschouris
Alexis  KelekisAlexis Kelekis
Alexis Kelekis
ACAngelos Charokopakis
Angelos Charokopakis
DKDimitrios A. Kelekis
Dimitrios A. Kelekis
Background This study examined the safety, pharmacokinetics, and efficacy of transarterial chemoembolization of hepatocellular carcinoma (HCC) using a newly developed size of a superabsorbent polymer drug-eluting embolic material. Methods Forty-five patients with documented HCC (Child–Pugh score A/B: 55.5 %/44.5 %) were embolized with HepaSphere microspheres 30–60 μm with escalation of lesion, dose, and frequency of re-embolization. Local response was evaluated with modified response evaluation criteria in solid tumors (mRECIST). Plasma levels of doxorubicin were measured in 24 patients at baseline and at 5, 20, 40, 60, and 120 min, at 6, 24, and 48 h, and at 7 days, respectively, to determine doxorubicin in plasma (Cmax) and area under the curve (AUC). Measurements of three patients who underwent lipiodol-based conventional chemoembolization (c-TACE) were also performed. Results TACE with HepaSphere was well tolerated with an acceptable safety profile and no 30-day mortality. Response rates were calculated on intention-to-treat basis with complete response (CR) in 17.8 % reaching 22.2 % for the target lesion. Overall partial response (PR) was seen in 51.1 %, stable disease in 20 %, and progressive disease in 11.1 % of patients. Overall objective response (CR + PR), including patients treated at all dosages of doxorubicin, was seen in 68.9 % of cases. After a median follow-up of 15.6 months, 1-year survival is 100 %. Doxorubicin AUC was significantly lower in patients with HepaSphere 30–60 μm (35,195 ± 27,873 ng × min/ml) than in patients with conventional TACE (103,960 ± 16,652 ng × min/ml; p = 0.009). Cmax was also significantly lower with HepaSphere 30–60 μm (83.9 ± 32.1 ng/ml) compared with c-TACE (761.3 ± 58.8 ng/ml; p = 0.002). Conclusion HepaSphere 30–60 μm is an effective drug-eluting embolic material with a favourable pharmacokinetic profile.

19 July 2010 in Arthritis Research & Therapy
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RARebecca Anderson
Rebecca Anderson
ÀFÀngels Franch
Àngels Franch
Margarida CastellMargarida Castell
Margarida Castell
Francisco José PerezFrancisco José Perez
Francisco José Perez
RBRolf Bräuer
Rolf Bräuer
RKRaimund W. Kinne
Raimund W. Kinne
Introduction: The objective of this study was to evaluate the efficacy of intravenous (i.v.) injection of liposomally encapsulated dexamethasone phosphate (DxM-P) in comparison to free DxM-P in rats with established adjuvant arthritis (AA). This study focused on polyethylene glycol (PEG)-free liposomes, to minimize known allergic reactions caused by neutral PEG-modified (PEG-ylated) liposomes.Methods: Efficacy was assessed clinically and histologically using standard scores. Non-specific and specific immune parameters were monitored. Activation of peritoneal macrophages was analyzedviacytokine profiling. Pharmacokinetics/biodistribution of DxM in plasma, synovial membrane, spleen and liver were assessedviamass spectrometry.Results: Liposomal DxM-P (3 × 1 mg/kg body weight; administered intravenously (i.v.) on Days 14, 15 and 16 of AA) suppressed established AA, including histological signs, erythrocyte sedimentation rate, white blood cell count, circulating anti-mycobacterial IgG, and production of interleukin-1beta (IL-1β) and IL-6 by peritoneal macrophages. The suppression was strong and long-lasting. The clinical effects of liposomal DxM-P were dose-dependent for dosages between 0.01 and 1.0 mg/kg. Single administration of 1 mg/kg liposomal DxM-P and 3 × 1 mg/kg of free DxM-P showed comparable effects consisting of a partial and transient suppression. Moreover, the effects of medium-dose liposomal DxM-P (3 × 0.1 mg/kg) were equal (in the short term) or superior (in the long term) to those of high-dose free DxM-P (3 × 1 mg/kg), suggesting a potential dose reduction by a factor between 3 and 10 by liposomal encapsulation. For at least 48 hours after the last injection, the liposomal drug achieved significantly higher levels in plasma, synovial membrane, spleen and liver than the free drug.Conclusions: This new PEG-free formulation of macrophage-targeting liposomal DxM-P considerably reduces the dose and/or frequency required to treat AA, with a potential to enhance or prolong therapeutic efficacy and limit side-effects also in the therapy of rheumatoid arthritis. Depot and/or recirculation effects in plasma, inflamed joint, liver, and spleen may contribute to this superiority of liposomally encapsulated DxM-P.

7 December 2006 in Mass Spectrometry Reviews
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CTConstantin Tamvakopoulos
Constantin Tamvakopoulos

22 June 2011 in Mass Spectrometry Reviews
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Theodora KatsilaTheodora Katsila
Theodora Katsila
ASAlexandros P. Siskos
Alexandros P. Siskos
CTConstantin Tamvakopoulos
Constantin Tamvakopoulos

1 November 2021 in Biochemical Pharmacology
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Journal Article
Open access
WMWalter H. Moos
Walter H. Moos
DFDouglas V. Faller
Douglas V. Faller
IGIoannis P. Glavas
Ioannis P. Glavas
DHDavid N. Harpp
David N. Harpp
NKNatalia Kamperi
Natalia Kamperi
KSKonstantina Sampani
Konstantina Sampani
Herein we trace links between biochemical pathways, pathogenesis, and metabolic diseases to set the stage for new therapeutic advances. Cellular and acellular microorganisms including bacteria and viruses are primary pathogenic drivers that cause disease. Missing from this statement are subcellular compartments, importantly mitochondria, which can be pathogenic by themselves, also serving as key metabolic disease intermediaries. The breakdown of food molecules provides chemical energy to power cellular processes, with mitochondria as powerhouses and ATP as the principal energy carrying molecule. Most animal cell ATP is produced by mitochondrial synthase; its central role in metabolism has been known for >80 years. Metabolic disorders involving many organ systems are prevalent in all age groups. Progressive pathogenic mitochondrial dysfunction is a hallmark of genetic mitochondrial diseases, the most common phenotypic expression of inherited metabolic disorders. Confluent genetic, metabolic, and mitochondrial axes surface in diabetes, heart failure, neurodegenerative disease, and even in the ongoing coronavirus pandemic.