Leondios Leondiadis

Effect of thymosin peptides on the chick chorioallantoic membrane angiogenesis model

The effect of alpha- and beta-thymosin peptides, namely prothymosin alpha (ProT(alpha)), thymosin alpha(1) (T(alpha)1), parathymosin alpha (ParaT(alpha)), thymosin beta(4) (Tbeta4), thymosin beta(10) (Tbeta10), and thymosin beta(9) (Tbeta9), on the angiogenesis process was investigated using the chick chorioallantoic membrane as an in vivo angiogenesis model. The thymosin peptides tested were applied in 10 microl aliquots containing 0.01-4 nmoles of Tbeta4, Tbeta10 or Tbeta9, 0.016-6.66 nmoles of T(alpha)1, 4.1 pmoles-1.66 nmoles of ProT(alpha), and 4.4 pmoles-1.76 nmoles of ParaT(alpha). Phorbol 12-myristate 13-acetate and hydrocortisone were also used as positive and negative control, respectively. Tbeta4, ProT(alpha) and T(alpha)1 were found to enhance angiogenesis, while Tbeta10, Tbeta9 and ParaT(alpha) exhibited an inhibitory effect on the angiogenesis process. When mixtures of Tbeta4 and Tbeta10 containing active amounts of the two peptides at different proportions were applied, the promoting effect of Tbeta4 on angiogenesis was reversed in the presence of increasing concentrations of Tbeta10 and vice versa. The effect of Tbeta10, Tbeta9, ProT(alpha) and ParaT(alpha), in parallel with Tbeta4 and T(alpha)1, on the angiogenesis process was investigated for the first time as far as we know and the results of this study offer more insight into the biological regulatory roles of thymosin peptides, and provide helpful information about their therapeutic potential. Whether these agents could be used either as inhibitors of angiogenesis in disease states where uncontrolled angiogenesis is involved, e.g. in carcinogenesis, or as angiogenesis promoters that could be useful in wound healing, fracture repair, peptic ulcers etc., remains to be further studied.

Analytical techniques for determining biotin

Biotin is a vitamin of the B-complex, which plays an important biochemical role in every living cell. In the recent years, the interest in this vitamin has been rekindled, mainly due to its association with serious human disorders, such as the inherited syndrome multiple carboxylase deficiency, which can be successfully treated with biotin administration. Diagnosis of biotin deficiency as well as monitoring of biotin levels in biological fluids of patients receiving biotin treatment is crucial. Equally important is the determination of biotin levels in pharmaceutical preparations as well as in food and food supplement products, which constitute the main source of biotin in humans. Several analytical methods for measuring biotin in various samples, e.g. human fluids, pharmaceutical formulations, food material etc., have been reported in the literature. In this review, the most representative of these methods are presented, and their characteristics are evaluated.

Levels of perfluorooctanesulfonate (PFOS) and perfluorooctanoate (PFOA) in blood samples from different groups of adults living in Greece

The production of perfluorinated compounds which finds application in a wide variety of consumer products has led to their accumulation in the environment. This fact, in combination with their chemical properties of amphiphilicity and chemical stability is the cause of their occurrence in human tissues, which according to reports is widespread, not only in occupationally exposed workers, but also in the general population. In this study, we analyzed 182 blood samples from three different groups of adults living in Greece, in order to evaluate blood levels of two environmentally most common perfluorinated compounds, perfluorooctanesulfonate (PFOS) and perfluorooctanoate (PFOA). The samples examined were from a group of individuals living in Athens, a group of inhabitants of the semi-urban and rural area of Argolida, and a group of cancer patients from the St. Savas Anticancer Hospital in Athens. The latter group was chosen in order to examine the possible relation of PFOS and PFOA levels with cancer incidence in the general population. The analytical results showed the presence of PFOS and PFOA in all samples examined, at levels similar to those reported from other European countries. There was no significant difference between the three groups however there was a significant difference between the levels of men and women in all groups examined. No correlation was found between age and PFOS and PFOA levels. This is the first study of this kind to be conducted in samples from Greece.

Differential expression of thymosins β4 and β10 during rat cerebellum postnatal development

The β-thymosins are a family of actin monomer-sequestering proteins widely distributed among vertebrate classes. The most abundant β-thymosins in mammalian species are thymosin β4 (Tβ4) and thymosin β10 (Tβ10), two small peptides (43 amino acids) sharing a high degree of sequence homology. In the present work, we have analyzed the distribution of Tβ4 and Tβ10 in the developing and adult rat cerebellum using in situ hybridization and immunohistochemistry techniques. Our results show that the temporal and cellular patterns of expression of both β-thymosins are different. In the young (7 and 18 postnatal days) and adult (1 and 4 months old) rat cerebellum, Tβ4 was mainly expressed in the glia (microglia, Golgi epithelial cells and oligodendrocytes), neurons (granule cells and Purkinje cells), and in the capillaries. In 14-month-old rats, the Tβ4 immunoreactivity was only detected in some microglia cells. In young and adult animals, most of the Tβ10 immunoreactivity was localized in several types of neuronal cells including granule cells, Golgi neurons and Purkinje cells. In old animals, a faint Tβ10 signal could be detected in a few Purkinje cells. Our results suggest that each β-thymosin could play a different function in the control of actin dynamics.

Levels of perfluorinated compounds in raw and cooked Mediterranean finfish and shellfish

Perfluorinated compounds (PFCs) were analyzed in several species of small Mediterranean fish and shellfish, all of which are popular in Greek diet. Analysis was conducted in raw samples and in samples cooked by the two ways preferred in Greek cuisine, i.e. fried in olive oil and grilled. PFCs above the detection limit were found in all raw samples except sardine, mussel and squid. The predominant PFC was PFOS (perfluorooctane sulfonate), the highest concentration of which was measured in picarel (20.4 ng g(-1) fresh weight). The PFOS values for the rest of the samples were between <LOD and 5.66 ng g(-1) fw. The concentrations of the detected PFCs were in most cases higher after frying or grilling, this increase being statistically significant. Based on these results, the Tolerable Daily Intake for PFOS and PFOA (perfluorooctanoic acid) through consumption of fish and seafood was well below the values proposed by EFSA.

Dioxin contamination after an accidental fire in the municipal landfill of Tagarades, Thessaloniki, Greece.

We report here a case study of dioxin contamination after a fire in the public landfill of Tagarades, which is situated southeast of Thessaloniki, Greece. The aim of this study was to determine the levels of PCDD/Fs and PCBs in food samples of meat, eggs, dairy products and vegetables, collected near the affected area, and to compare them with the usual levels found in Greek food. Soil samples were also gathered from various sites at a distance up to 5km from the landfill. Some food samples were found above the limits specified by the EU, while all food samples were above the usual levels of Greek food. The contaminated products were appropriately destroyed. The results of the soil and olive samples indicate a reverse correlation between dioxin contamination and distance from the contamination source. It should be noted that PCB levels were normal in all analyzed samples.

Synthesis and angiogenetic activity in the chick chorioallantoic membrane model of thymosin beta-15.

Thymosin beta-15 (Tbeta15), a 44 amino acid peptide (MW = 5173) localized in human prostate and breast cancer tissues was successfully synthesized in multigram quantities using Fmoc solid-phase peptide synthesis. The synthesized product was shown to have the right structure by ESI and MALDI mass spectral techniques and amino acid analysis. Relatively high yield was achieved, which might be due to enhanced acid stability of the p-cyanotrityl resin used. The effect of the synthesized Tbeta15 on the angiogenesis process was investigated using the chick chorioallantoic membrane (CAM) in vivo model. At concentrations above 1 microg/10 microl per disc, Tbeta15 exhibited a positive effect on angiogenesis, comparable to the effect of the intense angiogenetic factor phorbol 12-myristate 13-acetate at a standard concentration of 0.1 microg/10 microl per disc. The results of this study contribute to the further elucidation of the biological regulatory role of thymosin peptides and provide helpful information in the investigation of their possible therapeutic potential.

Determination of PCDD/F, dioxin-like PCB and PAH levels in olive and olive oil samples from areas affected by the fires in summer 2007 in Greece.

During the summer of 2007, a series of massive forest fires broke out in several areas across Greece. The main sources of PCDD/Fs and dioxin-like PCBs in Greece are considered to be the uncontrolled combustion of municipal solid waste in open landfills and accidental fires in forest, rural and industrial areas. Combustion may also lead to the formation of PAHs, which are fat soluble substances of considerable toxicity. The objective of this study was to investigate PCDD/F, dioxin-like PCB and PAH contamination of olive oil produced in fire-affected areas. Olive oil is a very significant agricultural product of Greece. Samples for this study were collected from all affected oil producing areas after the fire and 1year later. PCDD/Fs, dioxin-like PCBs and PAHs were at normal levels in all samples analysed.

Synthesis and characterization of novel natural product-Gd(III) MRI contrast agent conjugates

Several novel gadolinium chelates conjugated with paclitaxel, colchicine and thyroxine have been prepared as MRI contrast agents targeted to tubulin and thyroxine-binding globulin, respectively.

Perfluoroalkylated substances (PFASs) in home and commercially produced chicken eggs from the Netherlands and Greece

Dietary intake is a major route of human exposure to perfluoroalkylated substances (PFASs). However, the available information on PFAS levels in food, including chicken eggs, is limited. In the present study, home produced and commercially produced eggs (organic, battery and free range eggs) were collected from the Netherlands (n = 95) and Greece (n = 76). The egg yolks were analysed for 11 PFASs by liquid chromatography-tandem mass spectrometry using isotope dilution. PFAS levels in yolk were higher in home produced eggs from the Netherlands (median 3.1, range < LOQ - 31.2 ng g(-1)) and Greece (median 1.1, range < LOQ - 15.0 ng g(-1)) compared to the eggs collected from supermarkets. In these eggs, all PFAS levels were below the LOQ of 0.5 ng g(-1), except for a small amount of perfluorooctane sulfonate (PFOS) in 1 sample in each country (1.1 ng g(-1) and 0.9 ng g(-1) for the Netherlands and Greece respectively). PFOS was the predominant PFAS, making up on average 85% of ∑PFASs. The highest PFOS concentration was detected in a Dutch home produced egg sample (24.8 ng g(-1)). The contamination pattern was similar in both countries with the long-chain PFASs (C ≥ 8) being most frequently detected, while short-chain PFASs were rarely found. The most likely cause of the contamination of home produced eggs is ingestion of soil through pecking. Although regular consumption of home produced eggs will lead to an increased PFOS exposure, it is not expected that it will lead to exceedance of the tolerable daily intake established by EFSA.