Showing papers by "University of Crete published in 2000"

Waist circumference and waist-to-height ratio are better predictors of cardiovascular disease risk factors in children than body mass index.

Abstract: BACKGROUND: Visceral adipose tissue is associated with increased risk for cardiovascular disease risk factors and morbidity from cardiovascular diseases. Waist measurement and waist-to-height ratio (WHtR) have been used as proxy measures of visceral adipose tissue, mainly in adults. OBJECTIVE: To validate body mass index (BMI), waist circumference and WHtR as predictors for the presence of cardiovascular disease risk factors in children of Greek-Cypriot origin. SUBJECTS AND METHODS: A total of 1037 boys and 950 girls with mean age 11.4±0.4 y were evaluated. Dependent variables for the study were total cholesterol (TC), triglycerides (TG), high-density lipoprotein cholestrol (HDL-C), low-density lipoprotein cholesterol (LDL-C), and systolic (SBP) and diastolic (DBP) blood pressure. RESULTS: When children were divided into two groups according to the 75th percentile for BMI, waist circumference and WHtR, all dependent variables had higher mean values in the highest percentile groups in WHtR groups and almost all variables in BMI and waist circumference groups. Adjusted odds ratios for predicting pathological values of cardiovascular disease risk factors were slightly higher for the highest WHtR group for predicting lipid and lipoprotein pathological values and for the highest BMI groups in predicting high blood pressure measurement. Using stepwise multiple regression analysis to explain the variance of the dependent variables, waist circumference was the most significant predictor for all variables both for boys and girls, whereas BMI had the lowest predictive value for the detection of cardiovascular disease risk factors. CONCLUSION: Waist circumference and WHtR are better predictors of cardiovascular disease risk factors in children than BMI. Further studies are necessary to determine the cutoff points for these indices for an accurate prediction of risk factors.

From molecules to ecosystems through dynamic energy budget models.

Abstract: Summary 1. Dynamic energy budget (DEB) models describe how individuals acquire and utilize energy, and can serve as a link between diAerent levels of biological organization. 2. We describe the formulation and testing of DEB models, and show how the dynamics of individual organisms link to molecular processes, to population dynamics, and (more tenuously) to ecosystem dynamics. 3. DEB models oAer mechanistic explanations of body-size scaling relationships. 4. DEB models constitute powerful tools for applications in toxicology and bio

Potent inhibitory action of red wine polyphenols on human breast cancer cells.

Abstract: Breast cancer (one of the most common malignancy in Western societies), as well as esophagus, stomach, lung, bladder, and prostate cancer, depend on environmental factors and diet for growth and evolution. Dietary micronutriments have been proposed as effective inhibitory agents for cancer initiation, progression, and incidence. Among them, polyphenols, present in different foods and beverages, have retained attention in recent years. Red wine is a rich source of polyphenols, and their antioxidant and tumor arresting effects have been demonstrated in different in vitro and in vivo systems. In the present study, we have measured the antiproliferative effect of red wine concentrate, its total polyphenolic pool, and purified catechin, epicatechin, quercetin, and resveratrol, which account for more than 70% of the total polyphenols in red wine, on the proliferation of hormone sensitive (MCF7, T47D) and resistant (MDA-MB-231) breast cancer cell lines. Our results indicate that polyphenols, at the picomolar or the nanomolar range, decrease cell proliferation in a dose- and a time-dependant manner. In hormone sensitive cell lines, a specific interaction of each polyphenol with steroid receptors was observed, with IC(50)s lower than previously described. Interaction of polyphenols with steroid receptors cannot fully explain their inhibitory effect on cell proliferation. In addition, discrete antioxidant action on each cell line was detected under the same concentrations, both by modifying the toxic effect of H(2)O(2), and the production of reactive oxygen species (ROS), after phorbol ester stimulation. Our results suggest that low concentrations of polyphenols, and consecutively, consumption of wine, or other polyphenol-rich foods and beverages, could have a beneficial antiproliferative effect on breast cancer cell growth.

Microsatellite variability in grapevine cultivars from different European regions and evaluation of assignment testing to assess the geographic origin of cultivars

Abstract: Nine microsatellite markers (VVMD5, VVMD7, VVS2, ssrVrZAG21, ssrVrZAG47, ssrVrZAG62, ssrVrZAG64, ssrVrZAG79 and ssrVrZAG83) were chosen for the analysis of marker information content, the genetic structure of grapevine cultivar gene pools, and differentiation among grapevines sampled from seven European vine-growing regions (Greece, Croatia, North Italy, Austria and Germany, France, Spain and Portugal). The markers were found to be highly informative in all cultivar groups and therefore constitute a useful set for the genetic characterization of European grapevines. Similar and high levels of genetic variability were detected in all investigated grapevine gene pools. Genetic differentiation among cultivars from different regions was significant, even in the case of adjacent groups such as the Spanish and Portuguese cultivars. No genetic differentiation could be detected between vines with blue and white grapes, indicating that they have undergone the processes of cultivar development jointly. The observed genetic differentiation among vine-growing regions suggested that cultivars could possibly be assigned to their regions of origin according to their genotypes. This might allow one to determine the geographical origin of cultivars with an unknown background. The assignment procedure proved to work for cultivars from the higher differentiated regions, as for example from Austria and Portugal.

Fundamental quantum optics in structured reservoirs

Abstract: We review basic quantum electrodynamics and quantum optics aspects in microstructures that exhibit a gap in the spectrum of the electromagnetic radiation they support, known as photonic crystals. After a brief sketch of the properties of such materials we discuss the behaviour of few-level atoms or collections thereof with transition frequencies inside and in the vicinity of the gap. The discussion is cast in terms of a unified formalism which facilitates the comparison with standard cavity-atom physics.

Volatility Spillovers Between Stock Returns and Exchange Rate Changes: International Evidence

Abstract: In this paper, we have tested for volatility spillovers between stock returns and exchange rate changes for six countries, namely the US, the UK, Japan, Germany, Canada and France. Our findings can be summarised as follows. (a) Evidence of spillovers from stock returns to exchange rate changes is found for all countries except Germany. These results suggest that the asset approach to exchange rate determination is valid when formulated in terms of the second moments of the exchange rate distribution for these countries. (b) The spillovers from stock returns to exchange rate changes are symmetric in nature. (c) Volatility spillovers from exchange rate changes to stock returns are insignificant for all countries. The non-presence of spillovers from exchange rate changes to stock returns is in line with previous research which has focused on the first moments of the relevant distributions. (d) The correlation coefficient between the EGARCH filtered stock returns and exchange rate changes is negative and significant for all countries, indicating that there is a significant contemporaneous relationship between stock returns and exchange rate changes. (e) Volatility spillovers from stock returns spillovers to exchange rates have increased since the October 1987 crash, perhaps because financial markets have become more closely integrated during this period. © Blackwell Publishers Ltd. 2000.

TNF receptor family member BCMA (B cell maturation) associates with TNF receptor-associated factor (TRAF) 1, TRAF2, and TRAF3 and activates NF-kappa B, elk-1, c-Jun N-terminal kinase, and p38 mitogen-activated protein kinase.

Abstract: BCMA (B cell maturation) is a nonglycosylated integral membrane type I protein that is preferentially expressed in mature B lymphocytes. Previously, we reported in a human malignant myeloma cell line that BCMA is not primarily present on the cell surface but lies in a perinuclear structure that partially overlaps the Golgi apparatus. We now show that in transiently or stably transfected cells, BCMA is located on the cell surface, as well as in a perinulear Golgi-like structure. We also show that overexpression of BCMA in 293 cells activates NF-kappa B, Elk-1, the c-Jun N-terminal kinase, and the p38 mitogen-activated protein kinase. Coimmunoprecipitation experiments performed in transfected cells showed that BCMA associates with TNFR-associated factor (TRAF) 1, TRAF2, and TRAF3 adaptor proteins. Analysis of deletion mutants of the intracytoplasmic tail of BCMA showed that the 25-aa protein segment, from position 119 to 143, conserved between mouse and human BCMA, is essential for its association with the TRAFs and the activation of NF-kappa B, Elk-1, and c-Jun N-terminal kinase. BCMA belongs structurally to the TNFR family. Its unique TNFR motif corresponds to a variant motif present in the fourth repeat of the TNFRI molecule. This study confirms that BCMA is a functional member of the TNFR superfamily. Furthermore, as BCMA is lacking a "death domain" and its overexpression activates NF-kappa B and c-Jun N-terminal kinase, we can reasonably hypothesize that upon binding of its corresponding ligand BCMA transduces signals for cell survival and proliferation.

Detection and identification of Leishmania DNA within naturally infected sand flies by seminested PCR on minicircle kinetoplastic DNA.

Abstract: A seminested PCR assay was developed in order to amplify the kinetoplast minicircle of Leishmania species from individual sand flies. The kinetoplast minicircle is an ideal target because it is present in 10,000 copies per cell and its sequence is known for most Leishmania species. The two-step PCR is carried out in a single tube using three primers, which were designed within the conserved area of the minicircle and contain conserved sequence blocks. The assay was able to detect as few as 3 parasites per individual sand fly and to amplify minicircle DNA from at least eight Leishmania species. This technique permits the processing of a large number of samples synchronously, as required for epidemiological studies, in order to study infection rates in sand fly populations and to identify potential insect vectors. Comparison of the sequences obtained from sand flies and mammal hosts will be crucial for developing hypotheses about the transmission cycles of Leishmania spp. in areas of endemicity.

Recent experience with Pseudomonas aeruginosa bacteremia in patients with cancer: Retrospective analysis of 245 episodes.

Abstract: BACKGROUND Pseudomonas aeruginosa bacteremia is a serious and possibly fatal condition in patients with cancer. OBJECTIVES To ascertain the frequency, demographics, and predisposing factors for P. aeruginosa bacteremia in patients with cancer and to determine the efficacy of various therapeutic regimens. SUBJECTS AND METHODS Patient records of the Clinical Microbiology Laboratory, The University of Texas, M. D. Anderson Cancer Center, Houston, were reviewed. From January 1, 1991, through December 31, 1995, 245 eligible cases of P. aeruginosa bacteremia were identified. We examined the patient records for the underlying malignant neoplasm and its management, symptoms and signs of infection, culture results of appropriate specimens, antibiotic therapy, and outcome. We also compared our present experience with a previous analysis from this institution covering the period from January 1, 1972, to December 31, 1981. RESULTS The incidence of P. aeruginosa bacteremia has decreased compared with the previous study (2.8 vs 4.7 cases per 1000 admissions). It was most common in patients with acute leukemia (55 of 1000 registrations), and the frequency in this disease has not changed. Half of the patients were not in the hospital when they developed their infection. The overall cure rate was 80%, which was a significant (P<.001) increase compared with the 62% cure rate in the previous study. In this study, no significant difference in the cure rates was observed between monotherapy with a beta-lactam and combination therapy overall (P = .72), and in patients with shock (P = 1.0) and those with pneumonia (P = .60). The patients' initial neutrophil counts were not of prognostic value; however, the cure rate depended on subsequent changes in neutrophil count during therapy. CONCLUSIONS The frequency rate of P. aeruginosa bacteremia has decreased in patients with solid tumors but has remained unchanged in patients with acute leukemia. Antibiotic regimens for empirical therapy of neutropenic patients and especially patients with acute leukemia should still provide coverage against P. aeruginosa.

Wine antioxidant polyphenols inhibit the proliferation of human prostate cancer cell lines.

Abstract: The effect of different wine antioxidant polyphenols (catechin, epicatechin, quercetin, and resveratrol) on the growth of three prostate cancer cell lines (LNCaP, PC3, and DU145) was investigated. A dose- and time-dependent inhibition of cell growth by polyphenols was found at nanomolar concentrations. The proliferation of LNCaP and PC3 cells was preferentially inhibited by flavonoids (catechin, epicatechin, and quercetin), whereas resveratrol was the most potent inhibitor of DU145 cell growth. Possible mechanisms of action were investigated: 1) The competition of polyphenols for androgen binding in LNCaP cells revealed significant interaction only in the case of high concentrations of quercetin, at least at five orders of magnitude higher than the concentrations needed for cell growth inhibition. All other phenols showed low interactions. 2) Oxygen species production after mitogen stimulation and H2O2 sensitivity of these cell lines did not correlate with the observed antiproliferative effects, ruling out such a mode of action. 3) NO production revealed two different patterns: LNCaP and DU145 cells produced high concentrations of NO, whereas PC3 cells produced low concentrations. Phorbol ester stimulation of cells did not reveal any additional effect in LNCaP and DU145 cells, whereas it enhanced the secretion of NO in PC3 cells. Polyphenols decreased NO secretion. This effect correlates with their antiproliferative action and the inhibition of inducible NO synthase. It is therefore proposed that the antiproliferative effect of polyphenols is mediated through the modulation of NO production. In conclusion, our data show a direct inhibitory effect of low concentrations of antioxidant wine phenols on the proliferation of human prostate cancer cell lines mediated by the production of NO, further suggesting potential beneficial effects of wine and other phenol-containing foods or drinks for the control of prostate cancer cell growth.

X-Ray and Optical Variability in NGC 4051 and the Nature of Narrow-Line Seyfert 1 Galaxies

Abstract: We report on the results of a three-year program of coordinated X-ray and optical monitoring of the narrow-line Seyfert 1 galaxy NGC 4051. The rapid continuum variations observed in the X-ray spectra are not detected in the optical, although the time-averaged X-ray and optical continuum fluxes are well correlated. Variations in the flux of the broad Hβ line are found to lag behind the optical continuum variations by 6 days (with an uncertainty of 2-3 days), and combining this with the line width yields a virial mass estimate of ~1.1 × 106 M☉, at the very low end of the distribution of active galactic nucleus masses measured by line reverberation. Strong variability of He II λ4686 is also detected, and the response time measured is similar to that of Hβ but with a much larger uncertainty. The He II λ4686 line is almost 5 times broader than Hβ, and it is strongly blueward asymmetric, as are the high-ionization UV lines recorded in archival spectra of NGC 4051. The data are consistent with the Balmer lines arising in a low-to-moderate-inclination disklike configuration and the high-ionization lines arising in an outflowing wind, of which we observe preferentially the near side. Previous observations of the narrow-line region morphology of this source suggest that the system is inclined by ~50°, and if this is applicable to the broad Hβ-emitting region, a central mass of ~1.4 × 106 M☉ can be inferred. During the third year of monitoring, both the X-ray continuum and the He II λ4686 line went into extremely low states, although the optical continuum and the Hβ broad line were both still present and variable. We suggest that the inner part of the accretion disk may have gone into an advection-dominated state, yielding little radiation from the hotter inner disk.

Mechanism of the

Abstract: Stereochemical studies on [2 + 2] photoaddition of cis-/trans-4-propenylanisole (cis-1 and trans-1) and cis-1-(p-methoxyphenyl)ethylene-2-d(1) (cis-3-d(1)) to C(60) exhibit stereospecificity in favor of the trans-2 cycloadduct in the former case and nonstereoselectivity in the latter. The observed stereoselectivity in favor of the cis-6-d(3) [2 + 2] diastereomer by 12% in the case of the photochemical addition of (E)-1-(p-methoxyphenyl)-2-methyl-prop-1-ene-3,3,3-d(3) (trans-5-d(3)) to C(60) is attributed to a steric kinetic isotope effect (k(H)/k(D) = 0.78). The loss of stereochemistry in the cyclobutane ring excludes a concerted addition and is consistent with a stepwise mechanism. Intermolecular secondary kinetic isotope effects of the [2 + 2] photocycloaddition of 3-d(0) vs 3-d(1), and 3-d(6) as well as 5-d(0) vs 5-d(1), and 5-d(6) to C(60) were also measured. The intermolecular competition due to deuterium substitution of both vinylic hydrogens at the beta-carbon of 3 exhibits a substantial inverse alpha-secondary isotope effect k(H)/k(D) = 0.83 (per deuterium). Substitution with deuterium at both vinylic methyl groups of 5 yields a small inverse k(H)/k(D) = 0. 94. These results are consistent with the formation of an open intermediate in the rate-determining step.

The Gcn5 bromodomain co-ordinates nucleosome remodelling

Abstract: The access of transcription factors to eukaryotic promoters often requires modification of their chromatin structure, which is accomplished by the action of two general classes of multiprotein complexes1. One class contains histone acetyltransferases (HATs), such as Gcn5 in the SAGA complex2, which acetylate nucleosomal histones. The second class contains ATPases, such as Swi2 in the Swi/Snf complex3, which provide the energy for nucleosome remodelling. In several promoters these two complexes cooperate but their functional linkage is unknown4,5,6,7,8. A protein module that is present in all nuclear HATs, the bromodomain, could provide such a link9. The recently reported in vitro binding of a HAT bromodomain with acetylated lysines within H3 and H4 amino-terminal peptides10 indicates that this interaction may constitute a targeting step for events that follow histone acetylation. Here we use a suitable promoter to show that bromodomain residues essential for acetyl-lysine binding are not required in vivo for Gcn5-mediated histone acetylation but are fundamental for the subsequent Swi2-dependent nucleosome remodelling and consequent transcriptional activation. We show that the Gcn5 bromodomain stabilizes the Swi/Snf complex on this promoter.

Mediterranean diet of Crete: foods and nutrient content.

Abstract: Objectives To describe the traditional diet of Crete and evaluate the nutrient composition of 3 types of diet common in Crete by means of chemical analyses of composite food samples. To compare results with dietary analyses from a nutrient database developed at the University of Crete, Greece. Design Three composite diet samples were obtained based on 7-day weighed food records representing the traditional Cretan Mediterranean diet (diet A), typical diet of present-day Greek adolescents (diet B), and fasting diet of the Eastern Orthodox church (diet C). Analyses were performed chemically and using a nutrient database. Results Chemical analyses provided a definitive measure, for the first time, of the nutrient composition of the complete Greek diet as it was in the early 1960s. In comparing chemical analyses with nutrient database analyses, differences greater than 15% of the analyzed value were found in all 3 diets for cholesterol and some vitamins. The differences between analyzed and calculated values in total fat and saturated fat content were less than 15% in all diets. Applications/conclusions The present study provides 2 practical examples of the Mediterranean diet, which although widely publicized has rarely been analyzed chemically. Diet A has been shown to be related to the lowest rates for coronary heart disease and cancer mortality compared with the diets of the other populations of the Seven Countries study. As such, it could be recommended for health promotion and prevention of disease. Diet C contains even lower amounts of saturated fatty acids and would be excellent for patients with hypercholesterolemia. The high antioxidants in diet C probably maintain very low levels of low-density lipoprotein cholesterol. Dietary analyses of the Greek diet could be based on an operational database such as ours if further chemical analyses are performed on specific foods. These would result in improved precision of the database and possible extension into national food composition tables and a national dietary database. J Am Diet Assoc. 2000;100:1487-1493 .

Acetylation by PCAF Enhances CIITA Nuclear Accumulation and Transactivation of Major Histocompatibility Complex Class II Genes

Abstract: The class II transactivator (CIITA), the master regulator of the tissue-specific and interferon gamma-inducible expression of major histocompatibility complex class II genes, synergizes with the histone acetylase coactivator CBP to activate gene transcription. Here we demonstrate that in addition to CBP, PCAF binds to CIITA both in vivo and in vitro and enhances CIITA-dependent transcriptional activation of class II promoters. Accordingly, E1A mutants defective for PCAF or CBP interaction show reduced ability in suppressing CIITA activity. Interestingly, CBP and PCAF acetylate CIITA at lysine residues within a nuclear localization signal. We show that CIITA is shuttling between the nucleus and cytoplasm. The shuttling behavior and activity of the protein are regulated by acetylation: overexpression of PCAF or inhibition of cellular deacetylases by trichostatin A increases the nuclear accumulation of CIITA in a manner determined by the presence of the acetylation target lysines. Furthermore, mutagenesis of the acetylated residues reduces the transactivation ability of CIITA. These results support a novel function for acetylation, i.e., to regulate gene expression by stimulating the nuclear accumulation of an activator.

Proteins of the ETS family with transcriptional repressor activity.

Abstract: ETS proteins form one of the largest families of signal-dependent transcriptional regulators, mediating cellular proliferation, differentiation and tumorigenesis. Most of the known ETS proteins have been shown to activate transcription. However, four ETS proteins (YAN, ERF, NET and TEL) can act as transcriptional repressors. In three cases (ERF, NET and TEL) distinct repression domains have been identified and there are indications that NET and TEL may mediate transcription via Histone Deacetylase recruitment. All four proteins appear to be regulated by MAPKs, though for YAN and ERF this regulation seems to be restricted to ERKs. YAN, ERF and TEL have been implicated in cellular proliferation although there are indications suggesting a possible involvement of YAN and TEL in differentiation as well. Other ETS-domain proteins have been shown to repress transcription in a context specific manner, and there are suggestions that the ETS DNA-binding domain may act as a transcriptional repressor. Transcriptional repression by ETS domain proteins adds an other level in the orchestrated regulation by this diverse family of transcription factors that often recognize similar if not identical binding sites on DNA and are believed to regulate critical genes in a variety of biological processes. Definitive assessment of the importance of this novel regulatory level will require the identification of ETS proteins target genes and the further analysis of transcriptional control and biological function of these proteins in defined pathways.

Manganese citrate chemistry: Syntheses, spectroscopic studies, and structural characterizations of novel mononuclear, water-soluble manganese citrate complexes

Abstract: The first two mononuclear manganese citrate complexes, (NH4)4[MnII(C6H5O7)2] (1) and (NH4)5[MnIII(C6H4O7)2].2H2O (2) were synthesized in aqueous solutions near physiological pH values. They were isolated in their pure crystalline forms and characterized by elemental analyses and spectroscopic techniques, including UV/visible, electron paramagnetic resonance, Fourier transformed infrared, and magnetic susceptibility measurements. Compound 1 crystallizes in the monoclinic space group P2(1)/c, with a = 8.777(1) A, b = 13.656(3) A, c = 9.162(2) A, beta = 113.62(2) degrees, V = 1006.2(6) A3, and Z = 2. Compound 2 crystallizes in the triclinic space group P1, with a = 9.606(3) A, b = 9.914(3) A, c = 7.247(3) A, alpha = 91.05(1) degrees, beta = 105.60(1) degrees, gamma = 119.16(1) degrees, V = 571.3(3) A3, and Z = 1. The X-ray crystal structures of 1 and 2 revealed that, in both cases, the manganese ion is six-coordinate and is bound by two citrate ligands in a distorted octahedral fashion. In the case of complex 1, the citrate ion binds to Mn2+ as a triply deprotonated ligand, retaining the central carbon hydroxyl hydrogen, whereas, in the case of compound 2, the citrate ligand coordinates to Mn3+ as a fully deprotonated entity. Compound 2 contains water molecules of crystallization in the unit cell which, through extensive hydrogen-bonding interactions, bestow considerable stability upon the Mn(3+)-citrate assembly. There are significant contributions to the stabilities of the assembled lattices in 1 and 2 arising from the ammonium counterions neutralizing the high anionic charges of the complexes. The EPR spectra attest to the presence of paramagnetic Mn2+ and Mn3+ species in the solid state. Corroborative evidence is obtained from the magnetic susceptibility measurements in the range 5-300 K. Complexes 1 and 2 present clear cases of mononuclear manganese citrate species relevant to manganese speciation in biological media and potentially related to the beneficial as well as toxic effects of manganese on humans.

FIRM: a class of distributed scheduling algorithms for high-speed ATM switches with multiple input queues

Abstract: Advanced input queuing is an attractive, promising architecture for high-speed ATM switches, because it combines the low cost of input queuing with the high performance of output queuing. The need for scalable schedulers for advanced input queuing switch architectures has led to the development of efficient distributed scheduling algorithms. We introduce a new distributed scheduling algorithm, FIRM, which provides improved performance characteristics over alternative distributed algorithms. FIRM achieves saturation throughput 1 with lower delay than the most efficient alternative (up to 50% at high load). Furthermore, it provides improved fairness (it approximates FCFS) and tighter service guarantee than others. FIRM provides a basis for a class of distributed scheduling algorithms, many of which provide even more improved performance characteristics.

The mitochondrial genome of the mediterranean fruit fly, Ceratitis capitata.

Abstract: The complete sequence of the mitochondrial genome of Ceratitis capitata has been determined. The circular genome is 15 980 bp long and contains a standard gene complement, i.e. the large and small ribosomal RNA subunits, twenty-two transfer RNA (tRNA) genes and thirteen genes encoding mitochondrial proteins. When comparing the sequence to fragments previously sequenced from other isolates it becomes apparent that interstrain polymorphisms are not rare. These differences are potentially useful for the development of diagnostic tools for population analysis applications, such as determining the source of recent introductions. Moreover, they could help obtain a solution to the long-lasting controversy on the possible eradication of the Medfly from certain locations.