Biomedical subjects

I Georgiou

Publications and source records attributed to I Georgiou.

At least 37 records · Page 2Linked to original sources

PubMed2000

Arrayed primer extension: solid-phase four-color DNA resequencing and mutation detection technology.

The technology and application of arrayed primer extension (APEX) is presented. We describe an integrated system with DNA chip and template preparation, multiplex primer extension on the array, fluorescence imaging, and data analysis. The method is based upon an array of oligonucleotides, immobilized via the 5' end on a glass surface. A patient DNA is amplified by PCR, digested enzymatically, and annealed to the immobilized primers, which promote sites for template-dependent DNA polymerase extension reactions using four unique fluorescently labeled dideoxy nucleotides. A mutation is detected by a change in the color code of the primer sites. The technology was applied to the analysis of 10 common beta-thalassemia mutations. Nine patient DNA samples, each of which carries a different mutation, and four wild-type DNA samples were correctly identified. The signal-to-noise ratio of this technology is, on the average, 40:1, which enables the identification of heterozygous mutations with a high confidence level. The APEX method can be applied to any DNA target for efficient analysis of mutations and polymorphisms.

DNA↗

PubMed2000

Glutathione S-transferase null genotypes in transitional cell bladder cancer: a case-control study.

OBJECTIVES: This study was conducted (1) to examine whether the GSTM1 and GSTT1 null genotypes are risk factors for bladder cancer, and (2) to study a possible association of these genotypes with disease severity. METHODS: This case-control study was undertaken over a 21-month period and included 89 newly diagnosed transitional cell bladder cancer patients and 147 controls; both patients and controls originated from a defined population (residents of the loannina region, Northwestern Greece) and were similar with regard to mean age, male to female ratio and smoking habits. The GSTM1 and GSTT1 genotypes were identified by multiplex polymerase chain reaction on peripheral blood DNA samples. Genotype frequencies among patients and controls were assessed and the association of the genotypes with tumor grade and stage at presentation were statistically evaluated by the chi(2) test. RESULTS: The GSTM1 null genotype was strongly associated with bladder cancer. The odds ratio, attributable and population attributable risks were estimated at 2.76, 0.64 and 0.40, respectively. The correlation between the GSTM1 null genotype with stage, although not statistically significant, was estimated at an odds ratio of 2.6 for invasive disease. The correlation of GSTM1 null genotype with tumor grade did not yield a statistically significant result. The GSTT1 null genotype was not statistically associated with bladder cancer. CONCLUSION: According to our study, individuals with the GSTM1 null genotype carry a substantially higher risk for bladder carcinogenesis. The GSTM1 null genotype is not associated with more aggressive disease in terms of tumor grade, although there is a correlation between this genotype and stage of the disease.

Adult↗

PubMed2000

Increased prevalence of GSTM(1) null genotype in patients with myelodysplastic syndrome: a case-control study.

BACKGROUND AND OBJECTIVE: Myelodysplastic syndromes (MDS) are clonal disorders of bone marrow stem cells characterized by ineffective hematopoiesis leading to blood cytopenia; they often progress to acute myeloid leukemia (AML). The glutathione S-transferases (GST) detoxify various agents, including those implicated in MDS. Both GSTM(1) and GSTT(1) genes have "null" alleles and are polymorphic. We studied the impact of GTM(1) and GSTT(1) null genotypes on the MDS susceptibility, disease severity and laboratory indices with prognostic value for the syndrome. MATERIAL AND METHODS: In a hospital-based case-control study we analyzed lymphocyte DNA samples from 54 patients with MDS and 60 cancer-free controls matched for age, sex, smoking habits and origin. A multiplex polymerase chain reaction was used to genotype both GSTM(1) and GSTT(1) simultaneously. The chi(2) test was used for statistical evaluation of the data and the odds ratios and attributable risk and population attributable risk were also calculated. RESULTS: A significantly increased frequency of GSTM(1) null genotype was found among MDS patients (57.4%) compared to controls (33.3%) (p < 0.01), while the frequency of GSTT(1) null genotype was not significantly higher in MDS patients (11.1% vs. 6.66%). Neither GSTM(1) and GSTT(1) null genotype was associated with a particular category of the French-American-British (FAB) classification in the patients studied. Additionally, GSTM(1) null genotype was associated with a significant decrease in the absolute number of neutrophils among the MDS patients. CONCLUSIONS: Individuals with GSTM(1) null genotype may have increased susceptibility to MDS. Null genotypes do not seem to have be associated with FAB classification while they may be associated with putative prognostic factors.

Age Factors↗

PubMed1999

Molecular screening of fragile X (FRAXA) and FRAXE mental retardation syndromes in the Hellenic population of Greece and Cyprus: incidence, genetic variation, and stability.

This study presents the first large, population-based molecular investigation of the fragile X (FRAXA) and FRAXE mental retardation syndromes in the Hellenic populations of Greece and Cyprus. The aims of this population screening were to determine the prevalence of FRAXA and FRAXE syndromes among idiopathic mentally retarded (IMR) individuals, to estimate the incidence in the general population, and to investigate the molecular mechanism of instability and expansion of the FMR1-repeat. Ten FRAXA patients were identified to have either the full mutation (eight) or premutation (two) from a Hellenic population of 866 unrelated IMR individuals (611 males and 255 females, age range 3-25 years). No FRAXE patients were identified among the 611 IMR males. The incidence of FRAXA in the Hellenic population of Cyprus is estimated at 1 in 4,246 males. The repeat sites from the FMR1 and FMR2 alleles were accurately determined and showed similar distribution and frequencies with other population studies. The analysis of AGG interspersion within the FMR1-repeat in normal males revealed long, pure CGG repeats within the "gray zone" as well as variation within the 3' end showing polarity of instability. This finding supports the hypothesis that the AGG interspersion and the length of the pure repeat are major factors in determining allele stability. Analysis of FRAXAC1, DXS548, and FRAXAC2 identified particular alleles and haplotypes to have a significant association with either gray zone alleles or alleles >15 pure CGG repeats. We hypothesize that this subgroup of alleles and haplotypes are associated with long pure CGGs (>15 CGG) or 35 repeats and, having shared an evolutionary past, would have the tendency to expand.

Adolescent↗

PubMed1999

Fragile X premutations and (TA)n estrogen receptor polymorphism in women with ovarian dysfunction.

We studied five groups of women with ovarian dysfunction for the CGG expansion in FMR1 and a (TA)n polymorphism in the estrogen receptor gene: a) poor responders to ovarian stimulation as part of in vitro fertilization (n = 13); b) women with familial premature ovarian failure (POF) (n = 7); c) sporadic cases with POF (n = 16); d) FRAXA premutation carriers with POF (n = 7); and e) FRAXA premutation carriers without POF (n = 9). FRAXA premutation was found in one woman with familial POF. A significant association of familial POF and FRAXA premutation carriers with POF having low copy of the (TA)n polymorphism as compared to controls was observed. Our preliminary data suggest a potential role of the estrogen receptor in POF, and it may influence the variable age of menopause of the FRAXA premutation carriers.

Adult↗

PubMed1999

Association of estrogen receptor gene polymorphisms with endometriosis.

OBJECTIVE: To explore the association of the estrogen receptor two-allele (point) polymorphism and multiallele (microsatellite) polymorphism with endometriosis. DESIGN: Case-control study. SETTING: Genetics and Endoscopy Unit, Department of Obstetrics and Gynecology, Ioannina University HOSPITAL, Ioannina, Greece. PATIENT(S): Fifty-seven women with surgically and histologically diagnosed endometriosis of stages I-IV. INTERVENTION(S): Diagnostic laparoscopy. MAIN OUTCOME MEASURE(S): Frequency and distribution of the estrogen receptor gene polymorphisms. RESULT(S): There was a statistically significant difference between the patients and the controls in the frequency of the two-allele Pvu II polymorphism (0.72 vs. 0.49) and in the median repeats of the (TA)n multiallele polymorphism (15 vs. 20 repeats). In both groups, linkage was found between the fewer (TA)n repeats (range, 12-19) and the positive Pvu II polymorphism. CONCLUSION(S): The variability of the estrogen receptor gene likely contributes to the pathogenesis of endometriosis.

Adult↗

PubMed1999

Effect of recombinant human erythropoietin in preterm infants.

Twenty-five premature infants (mean gestational age+/-SD, 31.4+/-1.9 weeks) were administered subcutaneously recombinant human erythropoietin (rHuEpo) at a dose of 300 u/kg of body weight three times a week beginning on the third day of life and continuing for 6 weeks. The controls (n=23) were premature infants with a mean gestational age of 32.2+/-2.3 weeks who did not receive rHuEpo. Haematological indices, haemoglobin and serum phosphate (Pi), and red blood cell (RBC) phosphate metabolites (ATP, 2,3-DPG, RBCPi) were tested monthly until the 6th month and thereafter at the 9th and 12th months of life. The level of serum soluble transferrin receptors (sTfR) correlated significantly with rHuEpo (p<0.05). The ratio of sTfR to log (ferritin) was significantly higher (p<0.001) in the infants treated with rHuEpo than the controls. Intracellular organic and inorganic Pi changes were not affected by the Epo administration. The RBC 2,3-DPG seemed adequate in infants receiving rHuEpo.

2,3-Diphosphoglycerate↗

PubMed1999

Genotypes of N-acetyltransferase-2 and risk of bladder cancer: a case-control study.

PURPOSE: This study was conducted to examine whether certain slow N-acetylation genotypes could be risk factors for bladder cancer, and the possible association between specific genotypes and the severity of the disease at first diagnosis. MATERIALS AND METHODS: This case-control study included 89 patients with transitional cell bladder cancer (diagnosed over a period of 21 months) and 147 controls. N-acetyltransferase-2 (NAT-2) genotypes were identified by allele specific polymerase chain reaction (PCR) on peripheral blood DNA samples. The x2 test was used for statistical evaluation to compare the differences observed between patients and controls and the different genotypes with tumor grading and local staging at presentation. Relative, attributable and population attributable risks were estimated for the genotypes found to present a significantly increased frequency for bladder cancer. RESULTS: A statistically significant difference in the frequency of genotypes was found between the two groups. The patient group had the higher frequency of slow acetylation genotypes (p = 0.0016). Among slow acetylators, homozygotes 341C/341C and compound heterozygotes 341C/857A had the most excessive risk for bladder cancer (p = 0.0041 and 0.0031, respectively). The 341C/341C genotype was found to be associated with more aggressive disease, in terms of tumor grading at presentation (p <0.05). CONCLUSIONS: According to our data, slow acetylators with 341C/341C and 341C/857A genotypes carry a substantially higher odds ratio (3.73 and 12.46, respectively) for bladder carcinogenesis. Additionally, among the slow acetylators, 341C/341C homozygotes are likely to have a higher risk for more aggressive disease.

Adult↗

PubMed1999

Analysis of chromosomal aberrations in breast cancer by comparative genomic hybridization (CGH). Correlation with histoprognostic variables and c-erbB-2 immunoexpression.

The establishment of additional powerful prognostic markers in breast cancer patients is of unquestionable importance given that breast cancer is characterized by morphologic, biologic and genetic heterogeneity. In the present study we analyzed 8 primary invasive breast carcinomas by comparative genomic hybridization (CGH) in order to find and map the DNA copy number changes occurring in these tumors. Furthermore, in order to evaluate the potential prognostic significance, we compared these genetic changes with other histo- and immunopathologic prognostic variables, such as tumor type, tumor grade, lymph node status, estrogen receptors content and c-erbB-2 oncoprotein expression. All the studied cases showed a wide variety of gains and losses of chromosomal regions or arms distributed among 16 chromosomes with an average number of 6.12 aberrations per case. Although several genetic changes appeared to be common, none was unique or consistent in all the studied cases. The most consistent regions of gain were on 1q, 20q and 8q while the most common regions of loss on 3p and 6q. Accumulation of chromosomal changes were more frequently found in high grade ductal breast carcinomas with overexpression of c-erbB-2 oncoprotein in both lymph node-negative and lymph node-positive patients, whose tumors were positive for estrogen receptors. If any of these genetic changes identified by CGH in breast cancer patients carry prognostic information, regardless of stage or other factors predictive of biologic behavior, further investigation is needed.

Adult↗

PubMed1998

FRAXA and FRAXE prevalence in patients with nonspecific mental retardation in the Hellenic population.

Mutations at FRAXA and FRAXE loci are due to expansions of a CGG trinucleotide repeat and are characterized by mental retardation. Here we report a pilot screening survey by means of cytogenetic and molecular methods of 433 unrelated retarded individuals and their parents of Hellenic origin coming from various parts of Greece and Cyprus. The purpose of the study was to estimate the frequency of FRAXA mutation in individuals with nonspecific mental retardation without family history and phenotypic stigmata in the Hellenic population. Five FRAXA-positive children (1.15%) were identified, of whom four were found to carry a full mutation and one a premutation. Furthermore we present preliminary data on a screening of FRAXE mutation frequency. We screened 257 male patients with nonspecific mental retardation, finding none positive for FRAXE mutation.

Adolescent↗

PubMed1998

The role of deoxyribonuclease I in amniotic fluid during pregnancy and labour.

The purpose of this study was to detect the presence, and determine the normal values and the significance of DNase I in the amniotic fluid and in human placentas. Fifty-one pregnant women at 16-22 weeks of gestation and 89 women in spontaneous labour at term were recruited to the study. DNase I activity was measured in amniotic fluid and cytoplasmic extracts from the fetal portion of placentas by using a spectrophotometric technique (DNA precipitation assay) and nucleic acid electrophoresis, following degradation of the DNA by the enzyme. DNase I activity was undetectable in the placental cytoplasmic extracts. In the second trimester of pregnancy DNase I activity was detectable in amniotic fluid (2.3+/-0.64x10(5) U/l). During labour DNase I activity was also detectable, but reduced levels were observed in the presence of clear amniotic fluid, compared to second trimester levels, (1.9+/-0.44x10(5) U/l, P<0.001), whereas higher levels were found in the presence of meconium-stained amniotic fluid compared to both second trimester and clear amniotic fluid at labour (11.4+/-4.1x10(5) U/l, P<0.001 and P<0.001, respectively). Three out of 17 fetuses with meconium-stained amniotic fluid (18%) developed perinatal infection. In conclusion, the detection of DNase I activity in the amniotic fluid of second and third trimester indicates a physiological role in human pregnancy. DNase I activity normally decreases at term, compared to second trimester levels, but increases significantly in the presence of meconium.

Amniotic Fluid↗

PubMed1998

Recombinant human erythropoietin treatment of postpartum anemia. Preliminary results.

OBJECTIVES: The aim of this study was to investigate the efficacy of recombinant human erythropoietin (rHuEpo) in postpartum anemia. STUDY DESIGN: At the University Hospital of Ioannina, rHuEpo was administrated subcutaneously to twenty anemic women (hemoglobin [Hb]<10 g/dl), for 15 days following delivery; all were given iron and folic acid per os. Twenty other women (the control group) with postpartum anemia (Hb<10 g/dl), received only iron and folic acid. The Mann-Whitney U-test was used for the comparison of hematological indices between the two groups, on days 1, 3, 5, 10, 15 and 40 postdelivery. RESULTS: On day 3, reticulocyte counts were significantly higher in the women who received rHuEpo, as compared to the controls (P<0.05). The mean Hb value increased to >2 g/dl in the group undergoing rHuEpo therapy as compared to 0.7 g/dl in the control group on day 5 (P<0.05). Furthermore, two women in the control group required blood transfusions, while no transfusions were required by the rHuEpo group. CONCLUSIONS: rHuEpo administration is useful for a more rapid amelioration of hematological indices in women with postpartum anemia. Further, the dose given in this study was not associated with significant side-effects.

Adolescent↗

PubMed1998

Variation in the number of FMR1 microsatellite repeats in three subgroups of the Hellenic population.

Microsatellites have been used for human evolution and origin studies by comparing their frequency, diversity, and allele size. In this study we report the analysis of three microsatellite loci, FMR1 CGG and flanking DXS548 and FRAXAC2, in three separate groups of the Hellenic population: Athens, representing the general Hellenic population; Epirus (northwest Greece); and Cyprus. Significant variations in frequency and diversity were found in the three groups. Compared with Athens, Epirus had a tendency for longer alleles and a higher heterozygosity for DXS548. Cyprus had a frequency of CGG alleles similar to Athens but a low heterozygosity and a limited number of alleles at DXS548 and FRAXAC2. Allele differences of microsatellite loci not only are present in remote populations but also are evident between groups belonging to the same population. Microsatellite analysis could be a useful tool for identifying the origin of the founder chromosomes in intra-population studies and the time elapsed from the establishment of each population subgroup.

Alleles↗

PubMed1998

The thalassemia syndromes and pregnancy, molecular basis, clinical aspects, prenatal diagnosis.

Thalassemies are the most common inherited disorders, occur at high frequency in endemic regions as the Mediterranean countries, Middle East, North Africa, Asia, and are associated with hypochromic, hemolytic anemia. For several years, immigrations increased the possibility of transferring the thalassemic genes to Europe and North America. A review of the pathophysiology and molecular basis of the thalassemias is presented in this paper. The obstetrics problems in B-Thalassemic tract pregnants as the various degree non iron dependent anemia and her complications in pregnancy and the risk of producing a homozygous child, are discussed. Hematological analysis (Hb, H, MCV, MCH, MCHC) of 141-B-Thalasemic trait pregnants and 129 normal controls in each trimester of pregnancy were performed. The carrier screening program and application of prenatal diagnosis with introducing in techniques of DNA analysis were shown. Diagnostic difficulties and trends in clinical management of thalassemic pregnants are discussed. The most frequent types of Greeks and Italians alleles were shown as well as the frequent mutations in 58 B-Thalassemia examined allels in Epirus.

Alleles↗

PubMed1997

Feto-maternal bleeding following coelocentesis.

The potential risk of feto-maternal haemorrhage following coelocentesis was examined in 17 singleton pregnancies at 6-11 weeks of gestation by measuring maternal serum concentration of alpha fetoprotein (AFP) before and 1 and 10 min after the procedure. There was no significant difference between the maternal serum AFP concentration before coelocentesis (median 7.5, range 4.5-21.5 IU) compared to the values at 1 min (median 8.6, range 3.9-17.8; Z = -0.504, P = 0.614), and 10 min (median 7.5, range 5.7-20.6; Z = -0.432, P = 0.666) after the procedure. These findings demonstrate that coelocentesis is not associated with significant feto-maternal haemorrhage.

Female↗

PubMed1997

Oestrogen receptor gene polymorphisms and ovarian stimulation for in-vitro fertilization.

Experimental evidence has shown that mice lacking the oestrogen receptor (ESR) gene are infertile with cystic ovaries and follicular arrest. In humans, several polymorphisms and mutations in the ESR gene have been identified. In this study we have analysed a common PvuII and a rare BstUI polymorphism in the ESR gene. Analysis was carried out on DNA samples from women undergoing ovarian stimulation for in-vitro fertilization (IVF) and embryo transfer and controls having at least one pregnancy. Comparisons were done between the three PvuII genotypes, concerning the mean numbers of follicles and oocytes and the mean ratios of follicles to oocytes harvested in two consecutive cycles. Significantly lower ratios were identified in the group lacking the PvuII polymorphism, compared with the groups with heterozygous or homozygous PvuII polymorphisms (P > 0.05 and P > 0.01 respectively). The rare haplotype having both PvuII and BstUI restriction sites on one chromosome was present only in the IVF group. Pregnancies from IVF were significantly rarer in patients who were homozygous for the PvuII polymorphism (P > 0.05). Our results suggest that genetic variability in the ESR has a role in the quality of the ovarian follicles as judged by the ovarian response to stimulation and may also affect implantation.

Adult↗

PubMed1997

Prenatal diagnosis of beta-thalassaemia by coelocentesis.

Coelomic fluid and placental tissue were obtained from four women undergoing termination of pregnancy at 7-9 weeks gestation for psychological reasons. All four women and their partners were known carriers of beta-thalassaemia and DNA analysis in their blood identified the mutation carried by each of them. Allelespecific polymerase chain reaction and denaturing gradient gel electrophoresis techniques were used to detect and identify the mutations in the DNA extracted from the coelomic cells and placental tissue. Three fetuses were found to be carriers of either the paternal or maternal mutation, while one was found to be affected by beta-thalassaemia. There was concordance in the results obtained from the chorionic villi and coelomic cells. Amplification of the apolipoprotein B gene variable number tandem repeats (VNTR), in the DNA of the coelomic cells showed normal sagregation of alleles in the fetuses, thus excluding maternal contamination. The results of this study demonstrate that coelocentesis may be a reliable alternative technique for the diagnosis of beta-thalassaemia from as early as 7 weeks gestation.

Alleles↗

PubMed1997

Aplastic anemia. Report of a case with recurrent episodes in consecutive pregnancies.

BACKGROUND: Aplastic anemia complicating normal pregnancy is a rare event, associated with increased risks for both mother and fetus. CASE: A 30-year-old woman in her fifth pregnancy experienced the complications of aplastic anemia and preeclampsia. The patient had a history of four unsuccessful previous pregnancies also complicated by aplastic anemia, but she was free of the disease in the intervals between the pregnancies. During this last pregnancy she presented at 31 weeks' gestation with symptoms and signs of severe aplastic anemia and preeclampsia. A cesarean section was performed, and a normal infant was born. Supportive therapy, growth factors, prednisolone and intravenous immunoglobulin were administered, and the patient's general condition improved two weeks after delivery. CONCLUSION: Aplastic anemia may occur during consecutive pregnancies. The gestational age at the onset of the disease and the severity of the symptoms determine the outcome of the pregnancy.

Adult↗