The ACE I/D polymorphism in elite Greek track and field athletes.

AIM: The aim of this study was to examine genetic differences among 101 elite Greek track and field athletes and a representative random control group of 181 Greek individuals, by analyzing the I/D polymorphism in exon 16 of the ACE gene. METHODS: Athletes were defined as elite and included in the sample if they had been chosen to represent Greece at the international level. Amplification of DNA was carried out by polymerase chain reaction (PCR). The protein C reactive (PCR) products were separated by electrophoresis on agarose gel and were visualized by UV light. To avoid misclassification of ID genotypes, a second PCR was performed using specific primers. RESULTS: The ACE genotype and allele frequencies in the top power and endurance oriented athletes were not statistically significant different from those in a representative random sample of the Greek population. There was found only a trend towards an increased in frequency of the ACE DD genotype in the sprinters group (55.88% vs. 31.49%). CONCLUSIONS: The results suggest weak evidence that the ACE DD genotype could influence sprint performance in Greek athletes.

Microsatellite variability of wild and farmed populations of Sparus aurata.

The genetic diversity of Greek wild and farmed populations of Sparus aurata was investigated using seven microsatellite markers. Selective breeding programmes and founder effects have altered the composition of farmed populations leading to significant population differentiation between wild and cultured populations and lower allelic richness in farmed populations.

Intraspecific genetic variation of striped red mullet (Mullus surmuletus L.) in the mediterranean sea assessed by allozyme and random amplified polymorphic DNA (RAPD) analysis

Allozyme analysis on 20 putative enzyme-coding loci and RAPD analysis on 154 markers, amplified by eight decamer random primers, were used to assess the genetic variation of striped red mullet, Mullus surmuletus L., collected from six locations in the Mediterranean Sea. Both methods were able to detect a high degree of genetic polymorphism. For both methods, estimates of variance of allele frequencies (FST), and chi2 analyses, revealed significant differences (P < 0.05) among samples. Nei's genetic distance (D) among samples was low (mean D=0.011 for allozymes; mean D=0.018 for RAPDs) with data from both approaches revealing the sample from France to be most distinct from the Greek samples. Nevertheless, although most of the genetic variation in allozymes was not correlated with geographical distance, a correlation between genetic affinities and geographical area was found with RAPDs. It seems therefore that the RAPD method showed a more pronounced effect of isolation-by-distance in comparison with allozymes, probably because of the different number of markers of the red mullet genome examined with each method. Overall, the RAPD technique can be introduced as a complementary tool in the population genetics of marine fishes, providing supplementary information in their genetic stock structure analysis.

Induction of cytogenetic damage in human lymphocytes in vitro and of antineoplastic effects in Ehrlich ascites tumor cells in vivo treated by methotrexate, hyperthermia and/or caffeine.

The synergistic effect of methotrexate (at concentrations between 3. 1 and 100 nM) and its combinations with caffeine (618 microM) and/or hyperthermia (42 degreesC for 2 h) on the frequency of sister chromatid exchanges (SCEs), the proliferating rate index and the mitotic index in cultured human lymphocytes, was examined. Also, the in vivo antineoplastic effects of methotrexate (at a concentration of 0.45 microg/g body weight) and its combination with caffeine (120 microg/g body weight), both on the survival time and the increase of the weight of tumor of BALB/c mice inoculated with Ehrlich ascites tumor cells was examined in the present study. The results indicated that: (a) the triple combination of methotrexate, caffeine and hyperthermia synergistically increased the levels of SCEs and exerted cytostatic and cytotoxic action and (b) the combination of methotrexate and caffeine significantly increased the survival span of the mice inoculated with Ehrlich ascites tumor cells and reduced the increase of the weight of their tumors at rates higher than in the case of methotrexate by itself. It is suggested that the above triple combination (methotrexate plus caffeine plus hyperthermia) could achieve increased effectiveness of methotrexate, better therapy results, and could be successfully applied in the treatment of various types of cancer.

RFLP analysis of mitochondrial DNA to evaluate genetic variation in striped red mullet (Mullus surmuletus L.) and red mullet (Mullus barbatus L.) populations.

The genetic differentiation of striped red mullet (Mullus surmuletus) and red mullet (Mullus barbatus) was investigated in 6 Mediterranean populations of each species by means of restriction fragment length polymorphism analysis of mitochondrial DNA. Three segments amplified by polymerase chain reaction (control region, COI, and 12S-16S ribosomal RNA) were digested with 20 restriction endonucleases, revealing 71 haplotypes for M. surmuletus and 30 for M. barbatus. For the two species nucleotide diversity was equally distributed within and among populations, leading to N(ST) values of 0.545 and 0.500 for M. surmuletus and M. barbatus, respectively. However, intrapopulation and interpopulation genetic structuring appeared to be much higher for M. surmuletus than for M. barbatus (1.88% vs. 0.46% of mean intrapopulation nucleotide diversity; 1.94% vs. 0.47% of mean interpopulation nucleotide diversity; 0.055% vs. 0.002% of net interpopulation divergence). Furthermore, 81.69% of the haplotypes observed for M. surmuletus were unique, whereas 70.29% of M. barbatus individuals were grouped in 3 common haplotypes. Given that fishing pressure and population sizes are similar for both species, this differentiation could be attributed to differences in biological parameters and life histories between the two species, coupled with oceanographic conditions prevailing in the studied area.

Forensic evaluation of 10 STRs and two minisatellite loci in the Greek population.

Allele frequencies for 10 STRs and two minisatellite loci have been typed in a large sample of unrelated Greeks. The resulting database could be used for medico-legal cases.

Y-chromosomal STR haplotypes in a population sample from continental Greece, and the islands of Crete and Chios.

Eight Y-chromosomal short tandem repeats (STRs)--DYS19, DYS389-I, DYS389-II, DYS390, DYS391, DYS392, DYS393, and DYS385--were typed in a population sample (n = 113) of unrelated males from seven different regions of Greece (Macedonia, Thessaly, Epirus, Central Greece, Peloponnese, Crete Island, and Chios Island).

Aminoglycoside antibiotics: interaction with trimethaphan at the neuromuscular junctions.

Trimethaphan, a ganglionic blocking agent which is administered by intravenous drip to produce controlled hypotension during surgery, produces a complete neuromuscular blockade at the isolated phrenic nerve-hemidiaphragm preparation of the rat at a concentration of 0.3 mmol X l-1. This blockade is not reversed by neostigmine, a cholinesterase inhibitor, nor by calcium chloride, and this action is attributed to the local anaesthetic activity of the drug. Trimethaphan (1.5 X 10(-2) mmol X l-1) interacts with the following aminoglycoside antibiotics: gentamicin (0.04), streptomycin (0.05), netilmicin (0.06), amikacin (0.11), sisomicin (0.14), kanamycin (0.17), tobramycin (0.18) and dibekacin (0.21 mmol X l-1) to produce a complete neuromuscular blockade. These pharmacodynamic interactions of trimethaphan and aminoglycoside antibiotics occur at significantly reduced concentrations of the interacting drugs which are very close to the ones obtained after administration of therapeutic doses. When trimethaphan or aminoglycoside antibiotics are used alone at the above reduced concentrations they do not exert any neuromuscular blocking activity. The neuromuscular blockade which is obtained after the interaction of trimethaphan with aminoglycoside antibiotics is not reversed by either neostigmine or calcium chloride, although the neuromuscular blockade which is produced by aminoglycoside antibiotics alone is reversed by calcium chloride. It is concluded that the local anaesthetic effect of trimethaphan is the predominant factor of the mechanism of the above interactions. These interactions may produce severe respiratory disturbances (respiratory depression or apnoea) to the patients, during the perioperative period, which can be reversed only with artificial ventilation.

Pancuronium effect on the neuromuscular function of hypoglycemic rats.

An expected response in a hypoglycemic patient to a muscle relaxant formed the basis for the research presented in this study. There was no information available in the accessible literature and references gave no data on this subject. But because perioperative hypoglycemia is not unusual, we scheduled this experimental work. Four groups of 6 white adult Wistar albino rats were used in the study. Group A was the normoglycemia control group, with blood glucose levels of 80-120 mg/dl. Groups B, C and D were made hypoglycemic by i.v. injection of insulin 1 IU/100 g b.w. Blood glucose levels were reduced to 50% of the control values in hypoglycemic animals, which were sacrificed 40 min later. Phrenic nerve-hemidiaphragm preparations were placed in a 100 ml bath containing Paradelis-Zaimis solution, 37 degrees C, pH 7.2, aerated with O2/CO2:95/5%. After stabilization and recording of neuromuscular activity, pancuronium bromide was administered in doses of 1.5 x 10(-9) M in groups A and B, 3 x 10(-9) M in group D. Statistical analysis between A-B, A-C, A-D groups was done with Student's paired t test. Results showed that under hypoglycemic conditions the amount of pancuronium bromide needed for complete neuromuscular blockade was 2.5-fold greater than that needed in normoglycemic conditions. These findings suggest that the integrity of the neuromuscular junction is altered during hypoglycemia.

Neuromuscular blocking activity of aminoglycoside antibiotics.

The aminoglycoside antibiotics possess neuromuscular blocking activity; the potency of those antibiotics tested appears to be as follows: gentamicin greater than streptomycin greater than amikacin greater than sisomicin greater than kanamycin = tobramycin greater than kanendomycin = dibekacin. The neuromuscular blockade produced by these antibiotics is not reversed by neostigmine, whereas it is reversed by calcium. Calcium not only has the ability to restore the neuromuscular transmission but also to exert protective action against the neuromuscular blocking activity of aminoglycoside antibiotics; these antibiotics are also potentially capable of interacting with non-depolarizing muscle relaxant drugs (d-tubocurarine, pancuronium) or propranolol, a beta-adrenergic receptor blocking agent. This interaction results in respiratory depression and/or prolonged apnoea. Our findings lead to the assumption that amino-glycoside antibiotics are involved in the process of acetylcholine release by nerve impulses, antagonizing calcium ions.

A study of the mechanism of action of aminoglycoside antibiotics on the guinea pig vas deferens.

Aminoglycoside antibiotics inhibit contractility of the isolated guinea pig vas deferens in a dose-related manner. However, total inhibition of the contractility cannot be attained, a phenomenon most probably attributed to the partial inhibition of the function of Ca channels by the antibiotics. The inhibitory potency of aminoglycoside antibiotics was found to be: sisomicin greater than gentamicin greater than netilmicin greater than streptomycin greater than dactimicin greater than amikacin greater than kanamycin greater than kanendomycin greater than dibekacin greater than tobramycin. Ca2+ antagonize the action of aminoglycoside antibiotics on the vas deferens competitively. This observation indicates that the untoward effect of aminoglycoside antibiotics on contractility of the vas deferens can be attributed to their ability to interfere with Ca2+ entry through cell membranes of the tissue, a prerequisite for subsequent contraction. Above a specific threshold (7.5 mM) Ca2+ have a prophylactic effect on vas deferens and prevent the inhibitory action of ICmax doses of the antibiotics. Thus, Ca could be used as a prophylactic medium or as an antidote in restoring contractility of the vas deferens if it is inhibited by aminoglycoside antibiotics.

Effect of aminoglycoside antibiotics on the contractility of the uterus.

In the present study the inhibitory effect of five aminoglycoside antibiotics on the contractility of rat uterus was investigated. We found that all the antibiotics tested inhibited the contractility of the isolated rat uterus and only quantitative differences existed among them. The inhibitory potency of the aminoglycoside antibiotics appears to be as follows: sisomicin greater than gentamicin greater than tobramycin greater than dibekacin greater than amikacin. Calcium not only has the ability to restore the normal contractility of the uterus but also to exert protective action against the inhibitory effect of aminoglycoside antibiotics on the uterus contractility.

Interaction of aminoglycoside antibiotics with oxytocin and prostaglandin E2 on uterine contractility.

In the present study the interaction of aminoglycoside antibiotics with oxytocin and prostaglandin E2 on the contractility of the rat uterus was investigated. It was found that oxytocin and prostaglandin E2 were able to completely reverse the uterine relaxing effect of aminoglycoside antibiotics and when administered concomitantly they exert a protective action. These findings support the view that aminoglycoside antibiotics affect superficially bound extracellular calcium only, since oxytocin and prostaglandins primarily act on intracellular calcium.

Interaction of aminoglycoside antibiotics and calcium channel blockers at the neuromuscular junctions.

Aminoglycoside antibiotics (mmol.l-1) gentamicin (0.74), streptomycin (1.02), netilmicin (1.24), amikacin (2.23), sisomicin (2.74), dactimicin (2.75), kanamycin (3.43), kanendomycin (3.45), tobramycin (3.53) and dibekacin (4.35) produce a complete neuromuscular blockade at the isolated phrenic nerve-hemidiaphragm preparation of the rat, which is only reversed by calcium chloride. On the other hand, verapamil (2.04 mmol.l-1), a calcium channel blocker, also produces a complete neuromuscular blockade at the above preparation which is reversed by calcium chloride. Aminoglycoside antibiotics are potentially capable of interacting with verapamil and produce a complete neuromuscular blockade at concentrations significantly reduced. The neuromuscular blockade which is produced by the concurrent administration of the aminoglycoside antibiotics and verapamil is obtained with the usual therapeutic blood concentrations of the individual agents. Furthermore, the neuromuscular blockade which is produced during verapamil-aminoglycoside antibiotics interactions is completely reversed after calcium chloride administration. The mechanism by which aminoglycoside antibiotics and verapamil produce neuromuscular blockade must be the same. Both classes of drugs interfere with calcium ions movements through the calcium channels of the membrane of the motor nerve-endings inhibiting acetylcholine release at the synaptic cleft. The interaction of aminoglycoside antibiotics and calcium channel blockers is of clinical significance because when these agents are given concurrently during the perioperative period they may lead to respiratory depression or prolonged apnoea. These respiratory disturbances can be managed by slow intravenous infusion of 50 to 200 mg of calcium gluconate.

The influence of age on the distribution and activity of histamine receptors in the rat uterus.

In immature rat uterus histamine (10(-6) mol.l-1) potentiates by 25%, the carbachol (2 x 10(-6) mol.l-1) induced uterine contractions. This potentiation is abolished by mepyramine (6 x 10(-9) mol.l-1), an H1-receptor antagonist. Higher concentrations of histamine, up to 10(-4) mol.l-1, did not exert any inhibitory effect on carbachol-induced uterine contractions. In mature rat uterus carbachol-induced contractions are inhibited by histamine by about 25%. This inhibitory effect of histamine is significantly enhanced by mepyramine by about 50%. Inhibitory effects of higher concentrations of histamine, up to 10(-4) mol.l-1, are not enhanced by mepyramine. Cimetidine (4 x 10(-4) mol.l-1), an H2-receptor antagonist, abolished the inhibitory effects of histamine on carbachol-induced uterine contractions. In conclusion, in immature rat uterus there exists only H1 histamine receptors, activation of which exert an excitatory effect. In mature rat uterus there exists both H1 and H2 histamine receptors. The relaxant effect of histamine on mature rat uterus is exerted by activation of H2-receptors which predominate.

Phylogenetic relationships among four species of Mullidae (Perciformes) inferred from DNA sequences of mitochondrial cytochrome b and 16S rRNA genes.

DNA sequence comparisons of two mitochondrial DNA genes were used to infer phylogenetic relationships among four species of mullids. Approximately 238bp of the mitochondrial 16S ribosomal RNA (rRNA) and 261bp of the cytochrome b (cytb) genes were sequenced from representatives of three mullid genera (Mullus, Upeneus, Pseudopeneus), present in the Mediterranean Sea. Trees were constructed using three methods: maximum likelihood (ML), neighbor joining (NJ) and parsimony (MP). The results of the analyses of these data together with published data of the same mtDNA segments of two other perciform species (Sparus aurata, Perca fluviatilis), support the previous taxonomic classification of the three genera examined, as well as the classification of the two red mullet species in the same genus.

The ACTN3 gene in elite Greek track and field athletes.

The study of genetic influence in the making of an Olympic champion is still in its nascence, but recent work has provided findings regarding the association of the ACTN3 gene on athletic performance. The aim of this study was to examine genetic differences among elite Greek track and field athletes by analysing a mononucleotide polymorphism in exon 15 of the ACTN3 gene. Results showed that ACTN3 genotype and allele frequencies in the top power-oriented athletes were statistically significantly different from those in a representative random sample of the Greek population: the frequency of the RR ACTN3 genotype in power-oriented athletes vs. the general population was 47.94 % vs. 25.97 %. This result was even more prominent for comparison of the subgroup of sprinters to controls. The results suggest an overall strong association between the presence of the RR genotype and elite power performance.

Differential Y-chromosome Anatolian influences on the Greek and Cretan Neolithic.

The earliest Neolithic sites of Europe are located in Crete and mainland Greece. A debate persists concerning whether these farmers originated in neighboring Anatolia and the role of maritime colonization. To address these issues 171 samples were collected from areas near three known early Neolithic settlements in Greece together with 193 samples from Crete. An analysis of Y-chromosome haplogroups determined that the samples from the Greek Neolithic sites showed strong affinity to Balkan data, while Crete shows affinity with central/Mediterranean Anatolia. Haplogroup J2b-M12 was frequent in Thessaly and Greek Macedonia while haplogroup J2a-M410 was scarce. Alternatively, Crete, like Anatolia showed a high frequency of J2a-M410 and a low frequency of J2b-M12. This dichotomy parallels archaeobotanical evidence, specifically that while bread wheat (Triticum aestivum) is known from Neolithic Anatolia, Crete and southern Italy; it is absent from earliest Neolithic Greece. The expansion time of YSTR variation for haplogroup E3b1a2-V13, in the Peloponnese was consistent with an indigenous Mesolithic presence. In turn, two distinctive haplogroups, J2a1h-M319 and J2a1b1-M92, have demographic properties consistent with Bronze Age expansions in Crete, arguably from NW/W Anatolia and Syro-Palestine, while a later mainland (Mycenaean) contribution to Crete is indicated by relative frequencies of V13.