Ozlem Gok

SIRT1 Gene Polymorphisms Affect the Protein Expression in Cardiovascular Diseases

Cardiovascular disease (CVD), the leading cause of death worldwide, is related to gene-environment interactions due to epigenetic factors. SIRT1 protein and its downstream pathways are critical for both normal homeostasis and protection from CVD-induced defects. The aim of this study was to investigate the association between SIRT1 single nucleotide polymorphisms (SNPs) (rs7895833 A>G in the promoter region, rs7069102 C>G in intron 4 and rs2273773 C>T in exon 5 silent mutation) and SIRT1 and eNOS (endothelial nitric oxide synthase) protein expression as well as total antioxidant status (TAS), total oxidant status (TOS) and oxidative stress index (OSI) in CVD patients as compared to controls. The frequencies of mutant genotypes and alleles for rs7069102 and rs2273773 were significantly higher in patients with CVD compared to control group. The risk for CVD was increased by 2.4 times for rs7069102 and 1.9 times for rs2273773 in carriers of mutant allele compared with carriers of wild-type allele pointing the protective role of C allele for both SNPs against CVD. For rs7895833, there was no significant difference in genotype and allele distributions between groups. SIRT1 protein, TAS, TOS and OSI levels significantly increased in patients as compared to control group. In contrast, level of eNOS protein was considerably low in the CVD patients. An increase in the SIRT1 expression in the CVD patients carrying mutant genotype for rs7069102 and heterozygote genotype for all three SNPs was observed. This is the first study reporting an association between SIRT1 gene polymorphisms and the levels of SIRT1 and eNOS expressions as well as TAS, TOS and OSI.

A Remarkable Age-Related Increase in SIRT1 Protein Expression against Oxidative Stress in Elderly: SIRT1 Gene Variants and Longevity in Human

Aging is defined as the accumulation of progressive organ dysfunction. Controlling the rate of aging by clarifying the complex pathways has a significant clinical importance. Nowadays, sirtuins have become famous molecules for slowing aging and decreasing age-related disorders. In the present study, we analyzed the SIRT1 gene polymorphisms (rs7895833 A>G, rs7069102 C>G and rs2273773 C>T) and its relation with levels of SIRT1, eNOS, PON-1, cholesterol, TAS, TOS, and OSI to demonstrate the association between genetic variation in SIRT1 and phenotype at different ages in humans. We observed a significant increase in the SIRT1 level in older people and found a significant positive correlation between SIRT1 level and age in the overall studied population. The oldest people carrying AG genotypes for rs7895833 have the highest SIRT1 level suggesting an association between rs7895833 SNP and lifespan longevity. Older people have lower PON-1 levels than those of adults and children which may explain the high levels of SIRT1 protein as a compensatory mechanism for oxidative stress in the elderly. The eNOS protein level was significantly decreased in older people as compared to adults. There was no significant difference in the eNOS level between older people and children. The current study is the first to demonstrate age-related changes in SIRT1 levels in humans and it is important for a much better molecular understanding of the role of the longevity gene SIRT1 and its protein product in aging. It is also the first study presenting the association between SIRT1 expression in older people and rs7895833 in SIRT1 gene.

Melatonin attenuates phenytoin sodium-induced DNA damage

Abstract Phenytoin sodium (PHT Na+) is a potent antiepileptic drug against epileptic seizures and is used as a prophylactic treatment in traumatic brain injury. PHT Na+ leads to the formation of reactive oxygen species (ROS), and DNA is a crucial molecular target of ROS-initiated toxicity. Melatonin and its metabolites possess free-radical-scavenging activity. We therefore designed this study to investigate the potential protective effect of melatonin against PHT Na+-induced DNA damage by using the comet assay in a rat model in vivo. Thirty-three 3-month-old male Wistar rats were divided into five groups of control treated with isotonic sodium chloride (a single injection of isotonic sodium chloride and 100 µL in drinking water for 10 days), ethanol treated (in drinking water for 10 days containing 100 µL of ethanol in each 300-mL drinking bottle), melatonin treated (4 mg/kg body weight [b.w.] intraperitoneally [i.p.] at the start, in drinking water for 10 days), PHT Na+ treated (a single i.p. injection of 50 mg/kg) and PHT Na+ (50 mg/kg b.w., single i.p.) and melatonin (4 mg/kg b.w. i.p. at the start and 4 mg/kg in drinking water for 10 days) cotreated. To determine the protective effects of melatonin, the comet assay was performed using lymphocytes isolated in different time intervals (0, 15, 30, 45 and 60 minutes) from each group of animals. On days 1, 3, 7 and 10, blood samples were taken and the comet assay technique was performed. Our present data suggest that melatonin reversed PHT Na+-induced DNA damage.

Efficacy of statins on sirtuin 1 and endothelial nitric oxide synthase expression: the role of sirtuin 1 gene variants in human coronary atherosclerosis

Statins are 3‐hydroxy‐3‐methylglutaryl coenzyme A reductase inhibitors and are used to reduce the risk of coronary artery disease (CAD) due to their pleiotropic effects. Recently, greater focus has been placed on the role of sirtuin 1 (SIRT1) in cardiovascular disease research. However, insufficient data exist on the relationships between statins, SIRT1 protein levels, and SIRT1 gene variants. In the present study, we investigated the effects of statins, atorvastatin and rosuvastatin, in CAD patients by analysing the associations between SIRT1 gene variants, rs7069102C>G and rs2273773C>T, and SIRT1/endothelial nitric oxide (eNOS) expression, as well as total antioxidant and oxidant status, and the oxidative stress index. SIRT1 expression was significantly higher, and eNOS expression was significantly lower in CAD patients when compared with controls. Statin treatment reduced SIRT1 expression and increased eNOS expression, similar to the levels found in the control population, independent from the studied SIRT1 gene variants. Oxidative stress parameters were significantly increased in CAD patients, and were decreased by statin treatment, demonstrating the antioxidative effects of statins on atherosclerosis. These results indicate that statin treatment could produce its protective effect on cardiovascular disease through the inhibition of SIRT1 expression. This is the first study reporting on the effect of statins, specifically atorvastatin and rosuvastatin, on SIRT1 expression in CAD patients.

SIRT1 gene variants are related to risk of childhood obesity

AbstractObesity is a multifactorial disorder resulting from the interaction between genetic, psychological, physical, environmental, and socioeconomic factors. SIRT1 gene has important effects on the regulation of adiponectin, caloric restriction, insulin sensitivity, coronary atherosclerosis, and cardiovascular diseases. The aim of this study was to investigate the association between childhood obesity and SIRT1 gene polymorphisms regarding rs7895833 A > G in the promoter region, rs7069102 C > G in intron 4, and rs2273773 C > T in exon 5 using PCR-CTPP method in 120 obese and 120 normal weight children. In this study, BMI, systolic and diastolic blood pressure, LDL cholesterol, triglyceride, and insulin levels were significantly higher and HDL-cholesterol levels were significantly lower in obese children compared to normal weight children. For rs7895833 A > G, the rate of having AG genotype and G allele was significantly higher in obese children compared to non-obese group (p < 0.001). The risk for obesity was increased by 1.9 times in G allele carriers; therefore, A allele may be protective against obesity. Both study groups had CT heterozygote genotype for rs2273773 C > T. There was no significant difference for rs7069102 C > G gene polymorphism between groups. Conclusion: This is the first study reporting an association between SIRT1 gene polymorphisms and obesity in children.

Serum paraoxonase 1 activity and oxidative stress in pediatric patients with pulmonary tuberculosis.

Objectives: The aim of this study was to determine the oxidative stress and paraoxonase 1 (PON1) levels in children with pulmonary tuberculosis (TB) compared to healthy controls, and to examine the association of demographical with oxidative stress. Subjects and Methods: Forty children diagnosed with pulmonary TB and 40 age- and gender-matched healthy controls were enrolled in the study. Serum total antioxidant status (TAS), total oxidant status (TOS) and PON1 levels were measured. The oxidative stress index (OSI) was calculated to indicate the degree of oxidative stress. Results: The TAS levels were lower (1.73 ± 0.5 vs. 2.54 ± 1.2 μmol Trolox Eq/l) while TOS levels were significantly higher (26.9 ± 14.4 vs. 13.4 ± 7.7 μmol H2O2 Eq/l) in the TB group than in the controls (p < 0.001). The OSI was significantly higher in the TB group than in the controls (21.2 ± 5.1 vs. 6.5 ± 4.9 units, p = 0.006). Serum PON1 levels were significantly lower in the TB group than in the controls (14.2 ± 13.2 vs. 28.4 ± 17.3 U/l, p < 0.001). The lower PON1 levels correlated with TAS and OSI levels but not with anthropometric parameters (r = 0.264, p = 0.018 and r = -0.255, p = 0.023, respectively). Conclusion: The TOS and OSI levels were higher and the TAS and PON1 levels were lower in pediatric patients with pulmonary TB when compared to healthy controls. This indicates greater oxidative stress in the patients.

Altered expression of micro-RNA 199a and increased levels of cardiac SIRT1 protein are associated with the occurrence of atrial fibrillation after coronary artery bypass graft surgery

BACKGROUND Postoperative atrial fibrillation (POAF) is a potentially life-threatening complication after coronary artery bypass graft (CABG) surgery. The expression of the cardioprotective SIRT1 protein with its antioxidant activity is increased in cardiac tissue of patients suffering from POAF. So far, information is lacking about the relationship between SIRT1 regulating micro RNAs (miRs), SIRT1 protein and the occurrence of POAF. METHODS A total of 63 patients undergoing CABG were recruited, and biopsies were obtained from the right atrial appendage during cannulation. Postoperative, all patients were rhythm-monitored until discharge and randomized to POAF (n=20) or sinus rhythm (n=43). The expression of the micro RNAs miR-199a and miR-195 was quantified by real-time PCR. SIRT1 protein was detected by western blot analysis. RESULTS The relative expression of miR-199a in the POAF group was significantly decreased compared to the control group (0.77±0.27 vs. 1.11±0.69, P=.022) Accordingly, SIRT 1 protein was significantly induced in tissue probes of patients with POAF (P<.001). CONCLUSION Altered expression of the SIRT1 protein regulating miR-199a in human atrial tissue was found to be related to the occurrence of POAF, indicating its usefulness as a biomarker for cardiac surgery management.

The role of vitamin D receptor gene polymorphisms in Turkish infants with urolithiasis

Abstract Polymorphisms in the vitamin D receptor (VDR) gene have recently been reported to be associated with urinary calculi in pediatric and adult cases, but no studies have looked at the youngest period of life. The purpose of this study was to investigate the role of VDR gene polymorphisms in infantile urolithiasis in a Turkish population. We compared a study group of 104 infants (55 girls and 49 boys, mean age 6.94 ± 3.81 months) with a control group of 96 infants (51 girls and 45 boys, mean age 7.51 ± 3.23) to evaluate their demographics and metabolic risk factors. PCR-based restriction analysis of the polymorphisms on the VDR gene (BsmI and TaqI) showed statistically significant differences between study and control groups (p = 0.001 and 0.043, respectively). In addition, the prevalence of the BsmI genotype was significantly different between the hypercalciuric and normocalciuric stone formers (p = 0.007). Allelic frequencies were similar between the urolithiasis and control groups (p > 0.05). The B allele of BsmI and the A allele of ApaI were more prevalent in the hypercalciuric stone formers than in the normocalciuric stone formers (p = 0.018 vs.0.036, respectively). These results suggest that the BsmI and TaqI VDR genotypes could be candidate genes leading to infantile urolithiasis.

Parathyroid Allotransplant for Persistent Hypocalcaemia: A New Technique Involving Short-Term Culture.

OBJECTIVES To develop a new parathyroid allotransplant method for the treatment of permanent hypoparathyroidism. MATERIALS AND METHODS Parathyroid cells 50 × 10(6) derived from a parathyroid hyperplasia patient were transferred to a 61-year-old patient who had thyroidectomy 17 years earlier, allowing to papillary thyroid cancer; he was admitted to our outpatient clinic with symptomatic chronic hypocalcemia. Cell isolation, cryopreservation, and culturing were conducted according to a new protocol. RESULTS During a follow-up of 5 months, the patient had no complications that could indicate rejection, and clinical symptoms completely resolved without requiring any drug supplementation. CONCLUSIONS Here, we report a new method, enabling fast and cost-effective parathyroid allotransplant with maintained tissue viability sufficient to treat persistent hypocalcemia.

A novel non-surgical, minimally invasive technique for parathyroid autotransplantation: a case report.

We present a case report of intramuscular autotransplantation of the parathyroid cell suspension acquired after total parathyroidectomy. A 15‐yr‐old female patient who had been undergoing hemodialysis due to chronic renal failure for eight yr was diagnosed with secondary hyperthyroidism and subsequently underwent total parathyroidectomy. The parathyroid cells were acquired from the resected tissues, processed through isolation and cultivation phases, and counted using a cell counter. A total of two million cells were injected into the left deltoid muscle using a 22‐gauge needle. After surgery, five and 10 million cells were injected in the fifth and 12 week, respectively. The desired serum levels of parathyroid hormones and calcium were not achieved after the first two transplantations. In addition, there was no regression in the patients symptoms. However, at four wk after the third transplantation, serum parathyroid hormone level did not decrease to <3 pg/mL, the patient was asymptomatic, and the oral treatment was stopped. Our findings indicate that this new technique is applicable because it is minimally invasive, and it can be easily repeated.