Biomedical subjects
Publications and source records attributed to C Triantaphyllidis.
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).
The genetic structure of Silurus glanis (Europe's largest freshwater fish species) across most of its natural distribution was investigated using 10 microsatellite loci. The revealed levels of genetic diversity were much higher than previous allozyme and restriction fragment length polymorphism mitochondrial DNA analyses had shown; relative levels of variability among populations were however, in good agreement with the previous studies. Populations from large basins (Volga and Danube rivers) were the most polymorphic, while samples from the smaller Greek rivers, which are more prone to genetic bottleneck, exhibited the lowest levels of genetic diversity. Microsatellite multilocus genotyping permitted the assignment of individual fish to their population of origin with a score as high as 98.3%. Despite the great genetic differentiation of S. glanis populations, no consistent pattern of geographical structuring was revealed, in contrast to previous studies of European freshwater fish species. A model of isolation by distance seems more probable and a hypothesis of recent dispersion from only one glacial refugium is proposed. The discovery of the highest levels of microsatellite and mitochondrial diversity in the Volga sample and the presence of river connections, during the Pleistocene, between this area and all major areas of the present catfish distribution, place this refugium around the Ponto-Caspian region. Combining these data with those from previous studies, a number of markers are now available to monitor wild and hatchery populations even at the individual level.
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.
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.
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.
Founder analysis is a method for analysis of nonrecombining DNA sequence data, with the aim of identification and dating of migrations into new territory. The method picks out founder sequence types in potential source populations and dates lineage clusters deriving from them in the settlement zone of interest. Here, using mtDNA, we apply the approach to the colonization of Europe, to estimate the proportion of modern lineages whose ancestors arrived during each major phase of settlement. To estimate the Palaeolithic and Neolithic contributions to European mtDNA diversity more accurately than was previously achievable, we have now extended the Near Eastern, European, and northern-Caucasus databases to 1,234, 2, 804, and 208 samples, respectively. Both back-migration into the source population and recurrent mutation in the source and derived populations represent major obstacles to this approach. We have developed phylogenetic criteria to take account of both these factors, and we suggest a way to account for multiple dispersals of common sequence types. We conclude that (i) there has been substantial back-migration into the Near East, (ii) the majority of extant mtDNA lineages entered Europe in several waves during the Upper Palaeolithic, (iii) there was a founder effect or bottleneck associated with the Last Glacial Maximum, 20,000 years ago, from which derives the largest fraction of surviving lineages, and (iv) the immigrant Neolithic component is likely to comprise less than one-quarter of the mtDNA pool of modern Europeans.
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.
Explore the source record for details and available documents.
Two minisatellite (D1S80, D17S5) and 10 microsatellite (D2S1328, TPO, D3S1358, D9S926, D11S2010, THO1, VWF, FES, D16S310, and D18S848) polymorphic loci were analyzed in 5 Greek population groups (eastern Macedonia, central Macedonia, Thessaly, Epirus, and Greeks from Asia Minor) using the polymerase chain reaction. The genotypes at these loci conformed to Hardy-Weinberg equilibrium, and pairwise comparisons between them were in agreement with the expectation of independence between loci. This along with the low values of the coefficient of gene differentiation (GST) and the high heterozygosity levels of all loci allows the use of allele frequency data from the 12 hypervariable DNA markers for medicolegal casework in the Greek population groups studied. The small genetic distances indicate a genetic affinity among the 5 population samples. However, a few markers seem to allow some discrimination among the groups. No significant differences with other European populations were found for the loci studied.
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.
Twenty-three unrelated patients with tuberous sclerosis have been screened for the presence of mutations in six regions of the TSC2 gene. Eight novel intragenic polymorphisms have been found, one in intron 36 and seven in intron 4, with the use of SSCP analysis. Four of these polymorphisms alter the recognition sequence of specific restriction enzymes and can be detected as RFLPs. Study in a random sample of unrelated individuals from Northern Greece, showed that these polymorphisms have mean observed and expected heterozygosity values of 0.2996 and 0.3349, respectively and could be useful for linkage analysis. It is most likely that the wild type alleles from two pairs of these polymorphisms are strongly associated. A 667 bp segment of intron 4 (954 bp) and an additional 75 bp of intron 36 (352bp) were sequenced, thus completing the sequence of both introns.
To investigate the phylogenetic relationships and geographical structure among brown trout S. trutta L. Populations from the South Adriatic-Ionian and Aegean sea basins, mitochondrial DNA sequence comparisons were used. A 310-base-pair (bp) segment of the control region (D-loop), and an additional 280-bp segment of the cytochrome beta gene were sequenced from representatives of 13 brown trout populations. Phylogenetic analyses, conducted after combining the data presented with published data from other Eurasian brown trout, revealed four major phylogenetic groups, three of which were found widely distributed within the southern Balkan region. The phylogeographical patterns revealed by mtDNA represent one of the few cases where phylogenetic discontinuity in a gene tree exists without obvious geographical localization within a species' range and has most likely resulted from the differentiation of the major mtDNA clades during Messinian or early Pleistocene times. Finally, the genetic relationships among the populations suggested by mtDNA were generally not in accordance with either allozyme or morphological data.
The genetic differentiation and phylogenetic relationships of 13 populations (11 from Greece, one from Albania and one from France) of brown trout (Salmo trutta L.) were investigated at the mtDNA level. RFLP analysis of four segments of mitochondrial DNA (D-loop, cytochrome b and ND-5/6) amplified by PCR was used. Seven of 14 restriction endonucleases were found to detect variability in the ND-5/6 regions, whereas four and two out of 17 and 16 were polymorphic in the D-loop and cytochrome b, respectively. Eleven different haplotypes were observed. The observed interpopulation diversity was very high (mean = 1.65 per cent), whereas the intrapopulation diversity was low in most cases (mean = 0.063 per cent). Five phylogenetic assemblages were identified. The results demonstrate that Greece is one of the regions where brown trout display very high levels of genetic diversity. Most populations were genetically very distinct, possessing private mtDNA genotypes. Therefore, they represent unique gene pools which may warrant individual recognition for conservation and management. The genetic relationships among populations suggested by mtDNA data were not in accordance with allozyme data. This study illustrates the importance of considering the historical biogeography of a species in order to understand its population genetic structure. It also reinforces the view that mtDNA analysis represents a powerful tool to study past and present demographic phenomena.
Explore the source record for details and available documents.
The C3 complement types were studied in 463 patients with thyroid diseases and in 211 controls. There were no significant differences with respect to gene or phenotype frequencies between patient groups and controls. In the total sample, the gene frequencies are similar to those found in other European populations.
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.
Variations at the PGM1, GOTm, GOTs, and EsD loci were studied in placental samples from Northern Greece. The gene frequencies of GOTm and GOTs were found to be comparable with frequencies reported in other Caucasian populations. The frequencies of the EsD and PGMa11 alleles, however, were lower in Northern Greece than in other European populations.
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.