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N Akar

Publications and source records attributed to N Akar.

At least 19 recordsLinked to original sources
PubMed2006

Sequencing of the factor 8(F8) coding regions in 10 Turkish hemophilia A patients reveals three novel pathological mutations, and one rediagnosis of von Willebrand's disease type 2N.

The most common cause for severe cases of hemophilia A is the homologous recombination involving intron 22 and related sequences outside the F8 gene. F8 coding regions of the gene including the exon/intron junctions were sequenced in 10 Turkish hemophilia A patients all of whom have been typed negative for intron 22 inversion and who did not have a detectable change by DGGE analysis. Pathological changes including two novel deletions (c. 205del CT and c. 3699del ACAT), one novel missense mutation (9546A) and two recurrent missense mutations were observed in five patients. The c. 2110C > T is another novel pathological change affecting exonic splicing enhancer site in two patients. One of the remaining three patients had a recurrent vWD type 2N mutation in the F8 binding site of the vWF (C788R). The S1269S polymorphism (c. 3864A > C) detected phenotype. Conclusively, sequencing of the promoter and the coding regions of 10 hemophilia A patients contributes four novel pathological mutations to the F8 mutations list and reveals a rediagnosis of hemophilia A but is still not sufficient to confirm hemophilia A phenotype in two patients.

DNA Mutational Analysis↗
PubMed2006

Detection of virulence factors of Escherichia coli from children by multiplex polymerase chain reaction.

A total of 161 Escherichia coli (E. coli) strains isolated from children with urinary tract infection (UTI) were analysed for the genes encoding the virulence factors such as pyelonephritis (pap), s fimbriae (sfa), afimbrial adhesin I (afaI), haemolysin (hly), cytotoxic necrotising factor I (cnf I) and aerobactin (aer) by multiplex PCR. Ninety-four E. coli strains were found to carry at least one virulence factor. Therefore, 58.38% of total population was positive for one virulence gene at least. Percentage of genes within the total population for pap, sfa, afaI, hly, cnf I and aer was found as 22.98, 6.21, 9.94, 1.24, 9.94 and 39.75, respectively. Our analysis showed that sfa-pap (p < 0.001); pap-aer, afaI-aer and cnf I-pap (P < 0.05) and hly-sfa (p < 0.01) significantly co-occurred in their respective samples. In the light of these findings, we suggest an important role of pap causing UTI.

Base Sequence↗
PubMed2006

Plasminogen activator inhibitor-1 (PAI-1) gene polymorphism (-675 4G/5G) associated with obesity and vascular risk in children.

UNLABELLED: Atherothrombotic complications in insulin resistance are partly attributed to impaired fibrinolysis caused by increased PAI-1 plasma levels, and 4G/5G promotor polymorphism of the PAI-1 gene may modulate PAI-1 transcription. OBJECTIVE: To investigate PAI-1-675 4G/5G allele gene polymorphism and its relationship with obesity in children. CHILDREN AND METHOD: The study participants were 133 apparently healthy non-obese children, 24 probable exogenously obese without family history (Group I), 66 probable familial obese (Group II), and 44 obese children who were referred to the pediatric endocrinology department with any complication of obesity (Group III). Group I and Group II obese children were gathered from a school-based epidemiological study. RESULTS: Incidence of obesity was 19% in a school with high socio-economic status, whereas it was 4% in a school with low socio-economic status. Frequencies of 4G/4G gene polymorphisms were 24.81%, 37.50%, 64.80% and 61.11% in the control group, and groups I, II, and III, respectively. In groups II and III, 4G/4G gene polymorphism, and in non-obese control children 5G/5G gene polymorphism, was common. In obese children in the presence of family history for obesity and metabolic syndrome (odds ratio [OR]: 4.48, 95% confidence interval [CI]: 1.26-15.82), carriage of the 4G allele either in heterozygous or homozygous state increased the risk of vascular disease (OR: 6.10, 95% CI 1.64-22.90). In patients with acanthosis nigricans, high HOMA-IR values, hypertriglyceridemia and elevated atherogenic index, 4G/4G genotype frequency was remarkably higher compared to patients with other features of metabolic syndrome. CONCLUSION: The increasing prevalence of childhood obesity in high socio-economic status is associated with health risks. In obese children with family history of obesity and cardiovascular disease or type 2 diabetes mellitus and in obese children who had any feature of metabolic syndrome, frequency of 4G/4G genotype was more than the 4G/5G and 5G/5G genotypes in the PAI-1 gene. These patients can be at increased risk for developing vascular disease. Acanthosis nigricans, high HOMA-IR value, hypertriglyceridemia and high atherogenic index can also reflect the high risk of vascular disease in metabolic syndrome.

Adult↗
PubMed2005

Subtypes of genotype A Candida albicans isolates determined by restriction endonuclease and sequence analyses.

Systemic yeast infections are the Leading cause of mortality and morbidity in immunocompromized patients. Candida albicans, being the most frequently isolated fungal pathogen in these patients, can be divided into three genotypes (genotypes A, B and C) by 25S intron analysis. In our study, we found that molecular sizes of genotype A C. albicans isolates were heterogeneous. In order to determine the molecular basis of this difference, Haelll digestion was applied, and strains forming different band patterns were analyzed by automated sequence analysis. As a result of sequence analysis, eight different subtypes (a --> h) were found among genotype A C. albicans strains and an easy differentiation scheme consisting of Haelll and MspI digestions was constructed.

Base Sequence↗
PubMed2005

Evidence for single origins of 35delG and delE120 mutations in the GJB2 gene in Anatolia.

Eighteen different sequence changes, including three novel alterations, were detected in GJB2, encoding connexin 26, in 371 Turkish probands with non-syndromic sensorineural hearing loss. Two frequently detected mutations, 35delG and delE120, were shown to have single origins based on the conserved genotypes of two closely linked microsatellite and five single nucleotide polymorphism markers. Carrier frequencies of 35delG and delE120 in Egypt and Turkic populations of the Near East provide insights about the origin of these two mutations.

Adolescent↗
PubMed2004

Y chromosomal haplogroup J as a signature of the post-neolithic colonization of Europe.

In order to attain a finer reconstruction of the peopling of southern and central-eastern Europe from the Levant, we determined the frequencies of eight lineages internal to the Y chromosomal haplogroup J, defined by biallelic markers, in 22 population samples obtained with a fine-grained sampling scheme. Our results partially resolve a major multifurcation of lineages within the haplogroup. Analyses of molecular variance show that the area covered by haplogroup J dispersal is characterized by a significant degree of molecular radiation for unique event polymorphisms within the haplogroup, with a higher incidence of the most derived sub-haplogroups on the northern Mediterranean coast, from Turkey westward; here, J diversity is not simply a subset of that present in the area in which this haplogroup first originated. Dating estimates, based on simple tandem repeat loci (STR) diversity within each lineage, confirmed the presence of a major population structuring at the time of spread of haplogroup J in Europe and a punctuation in the peopling of this continent in the post-Neolithic, compatible with the expansion of the Greek world. We also present here, for the first time, a novel method for comparative dating of lineages, free of assumptions of STR mutation rates.

Africa, Northern↗
PubMed2004

Genotype distribution of Candida albicans isolates by 25S intron analysis with regard to invasiveness.

The aim of this study was to genotype Candida albicans strains isolated from patients with invasive and non-invasive deep-seated infections. For this purpose, 301 C. albicans isolates (81 invasive and 220 non-invasive) were genotyped by using specific PCR primers designed to span the transposable group I intron of the 25S rDNA gene. Fifty-three of the 81 invasive isolates were genotype A (65.4%), eight were genotype B (9.9%) and 20 were genotype C (24.7%), while 98 of the 220 non-invasive isolates were genotype A (44.6%), 46 were genotype B (20.9%) and 76 were genotype C (34.5%). Genotype A was more prevalent among invasive isolates and genotypes B and C were more prevalent among non-invasive isolates (P = 0.0046). Genotypes D and E which represent C. dubliniensis were not found. These results indicate that there may be a relationship between C. albicans genotypes and invasiveness; genotype A being more invasive than others. The presence or absence of the transposable group I intron in the 25S rDNA gene may be important in determining the invasiveness of C. albicans.

Adolescent↗
PubMed2004

Alterations in serum growth hormone (GH)/GH dependent ternary complex components (IGF-I, IGFBP-3, ALS, IGF-I/IGFBP-3 molar ratio) and the influence of these alterations on growth pattern in female rhythmic gymnasts.

BACKGROUND AND AIM: Normal growth in children is regulated to a great extent through the actions of the GH/IGF-I axis, a system consisting of GH and its mediators (ternary complex) that modulate growth in many tissues. The ternary complex (IGF-I/IGFBP-3/ALS) provides an acute regulatory mechanism in which IGF-I may be mobilized from the circulating reservoir of 150 kDa complexes to the tissues. Acute exercise is known to be a stimulus for GH secretion. The beneficial effects of scheduled exercise on body composition are also well established. However, the impact of strenuous exercise on the pubertal development of child athletes is still not well understood. The first goal of this study was to assess the acute effects of high intensity exercise training on GH-dependent ternary complex components in female rhythmic gymnasts compared to age-matched healthy female controls with normal physical activity. The second goal was to explore the influence of these exercise-induced changes on skeletal and pubertal growth in the same group prospectively over a period of 4 years. SUBJECTS AND METHODS: Seventeen female rhythmic gymnasts, aged 11.4 +/- 0.9 years, who had 10 h per week intense exercise for at least 4 months volunteered to participate in this study. Anthropometric measurement of height (Height SDS for chronological age [HtSDS(CA)], parentally adjusted height, predicted adult height), bone age and weight (BMI) were made using standard techniques in gymnasts and controls (aged 12.5 +/- 3.0 years, n = 12). Gymnasts were followed up to 4 years to observe growth velocity and pubertal progression. In order to determine the acute impact of exercise on levels of GH and GH-dependent ternary complex component (IGF-I, IGFBP-3, ALS, IGF-I/IGFBP-3 molar ratio), blood samples were obtained from gymnasts after a routine 2-h high-intensity training program and then after a 2-day rest period. These results were compared with age-matched controls with no scheduled sports activity. RESULTS: Despite the significant increment in serum GH and GH-dependent components immediately following the exercise, serum GH/IGF-I levels showed a significant decrement (p < 0.01) after a 2-day rest in gymnasts, to a nadir as low as those of the control subjects' baseline levels (p < 0.01). There was no difference in anthropometric characteristics of gymnasts and controls except BMI; gymnasts were leaner than controls. During a 4-year follow up, there were no differences between the gymnasts and controls in regard to skeletal growth and reaching their predicted height. However, in gymnasts there was a delay in pubertal tempo but not in growth. CONCLUSION: Intense exercise induces an acute rise in GH levels, but this acute elevation rapidly normalizes after a 2-day rest in female rhythmic gymnasts. These fluctuations in serum GH and GH-dependent ternary complex components had no reflection on the skeletal growth patterns in gymnasts over the 4-year follow up but there was a delay in their pubertal progression.

Adolescent↗
PubMed2003

Frequency of mtDNA A1555G and A7445G mutations among children with prelingual deafness in Turkey.

UNLABELLED: Considerable differences on the frequencies of the mitochondrial 12S rRNA A1555G and tRNA(Ser(UCN)) A7445G mutations have been reported in different populations. Our screening of 168 patients coming from independent Turkish families with prelingual sensorineural non-syndromic deafness revealed three deaf children with A1555G (1.8%) but no examples of A7445G. One proband with the mitochondrial A1555G mutation has also evidence for right parietal infarct on a brain imaging study, for which common thrombotic mutations were found to be negative. CONCLUSION: This study shows that the mitochondrial A1555G mutation is among the significant causes of prelingual non-syndromic deafness in the Turkish population.

Adolescent↗
PubMed2003

Moderate hearing loss and pseudodominant inheritance due to L90P/35delG mutations in the GJB2 (connexin 26) gene.

Mutations in the GJB2 (connexin 26-Cx26) gene are responsible for 20-50% of cases with prelingual non-syndromic deafness in a large part of the world including Turkey. Although most of the cases with Cx26 deafness have a recessive mode of inheritance, a small group of families demonstrated dominant or pseudodominant inheritance. In this report we present a Turkish family in which the proband had congenital profound deafness and was found to be homozygous for the 35delG mutation, whereas the father and a paternal uncle who had milder, late-onset sensorineural hearing loss had compound heterozygous 35delG and L90P mutations. This family and previous reports with the L90P mutation demonstrate that the hearing loss associated with the L90P/35delG genotype is consistently milder than that of 35delG homozygotes. GJB2 gene screening should be considered in families with seemingly dominant inheritance and late-onset moderate hearing loss.

Adult↗
PubMed2002

657del5 mutation in the NBS1 gene is associated with Nijmegen breakage syndrome in a Turkish family.

We report on a consanguineous Turkish family whose first son died of anal atresia and whose second son presented with severe pre- and post-natal growth retardation as well as striking microcephaly, immunodeficiency, congenital heart disease, chromosomal instability and rhabdomyosarcoma in the anal region. The proband was found to carry the homozygous 657del5 mutation in the NBS1 gene, which is responsible for Nijmegen breakage syndrome (NBS) in most of the Slav populations. Our family, the first diagnosed with NBS in the Turkish population, represents one of the most severely affected examples of the syndrome, with profound pre- and post-natal growth retardation associated with structural abnormalities, and expands the clinical spectrum of this rare disorder.

Abnormalities, Multiple↗
PubMed2002

Factor V 1691 G-A mutation in children with intracardiac thrombosis: a prospective study.

UNLABELLED: The objective of this study was to determine the association between intracardiac thrombosis and hereditary causes of thrombophilia, including factor V 1691 G-A (factor V Leiden, FVL) and prothrombin 20210 G-A mutations. Over a period of 3 y, genetic risk factors were evaluated in 13 consecutive children (mean age 6.27 +/- 5.44 y) with intracardiac thrombosis, diagnosed by cross-sectional echocardiography. Thrombi were localized in the left heart in four patients and the right heart in nine patients. All children had predisposing factors for thrombus formation: ventriculoatrial shunt for hydrocephalus (n = 3), indwelling catheter for chemotherapy (n = 5), cardiomyopathy (n = 2), sepsis (n = 1), homocystinuria (n = 1) and tetralogy of Fallot (n = 1). Six of the 13 children with intracardiac thrombosis were heterozygotes for FVL mutation. Three of these six children with FVL mutation had ventriculoatrial shunt for hydrocephalus, two children had cardiomyopathy and one had sepsis. None of the patients carried the prothrombin 20210 G-A mutation. CONCLUSION: It is recommended that FVL mutations should be investigated in all cases of intracardiac thrombosis irrespective of whether or not a predisposing factor is identified. When a predisposing factor is found antithrombotic prophylaxis may be considered in patients carrying the FVL mutation.

Adolescent↗
PubMed2002

The role of thrombophilic risk factors in the severity of pulmonary thromboembolism.

High plasma factor-VIIIc concentration, presence of factor-V 1691 G-A (FVL) and prothrombin20210A (PT20210A) mutations were shown to be significant risk factors for venous thromboembolism (VTE) and recurrent VTE. The objective of this study was to investigate the role of these thrombotic risk factors in the severity of pulmonary thromboembolism (PTE). The plasma concentrations of factor VIIIc, presence of FVL and PT20210A mutations were studied in 32 patients with PTE. Eleven of the patients had documented recurrent VTE. Lung perfusion scans were scored according to the percentage of vascular obstruction. Patients who had a pulmonary vascular obstruction score (PVOs) >50% were compared to those with PVOs <50%. There was no significant difference between the patients with PVOs >50% and those with PVOs <50%, with regard to the presence of FVL and PT20210A mutation. However, patients with PVOs >50% had a significantly higher factor-VIIIc concentration than those with PVOs <50% (factor-VIIIc levels were 253.3 +/- 29.1 International Units (IU) x dL(-1) and 138.5 +/- 16.2 IU x dL(-1), respectively; p<0.005). Factor-VIIIc concentrations were significantly correlated with PVOs (r=0.52, p<0.005). Patients with recurrent VTE had significantly higher factor-VIIIc concentrations than those in which it occurred for the first time (factor-VIIIc concentrations were 232.6 +/- 30.9 IU x dL(-1) and 158.3 +/- 20.6 IU x dL(-1), respectively; p<0.05). The authors conclude that in addition to being a risk factor for venous thromboembolism, high factor-VIIIc concentration is an important factor in the severity of pulmonary thromboembolism.

Factor V↗