Elif Ozkok

Losartan may prevent the elevation of plasma glucose, corticosterone and catecholamine levels induced by chronic stress

Introduction Stress is a stimulus that activates the hypothalamic pituitary adrenal (HPA) axis and sympathetic nervous system (SNS). Increased activity of the SNS causes to increment or impairment in blood pressure, heart rate, body temperature and plasma glucose and adrenocorticotrophic hormone (ACTH) levels. Angiotensin II (Ang II), which is a product of the renin-angiotensin system (RAS), is an important factor affecting the activity of the SNS and responses to stress. We suggest that the blockade of Ang II may be worthwhile in the prevention and treatment of diabetes mellitus and cardiovascular diseases affected by stress. Therefore, we investigated the effects of immobilisation stress on blood glucose, norepinephrine (NE), epinephrine (E) and corticosterone levels and the effects of an Ang II receptor antagonist, losartan, on these parameters. Materials and methods The rats were kept in small cylindrical cages for 60 min/day for 10 consecutive days to perform chronic immobilisation stress. Losartan (10 mg/kg) was given daily by gavage to Losartan (L) and Losartan + Chronic Stress (L+CS) groups. Control (C) and Chronic Stress (CS) P groups received an equal volume of saline daily by gavage for 10 days. After the last stress regimen, blood samples were collected for plasma glucose, NE, E and corticosteroid measurements. Results Plasma glucose, NE, E and corticosterone levels in the CS Group increased significantly compared with the C group. In Group L+CS, the plasma glucose, NE, E and corticosterone levels decreased significantly vs. Group CS. In Group L there was no significant difference vs. Group C. Conclusion It can be speculated that chronic blockade of RAS may decrease the excess sympathetic responses to stress in cardiovascular diseases and prevent the likely development of Type II diabetes mellitus.

DNA Repair Genes in Parkinson's Disease

AIMS There is a growing interest in the understanding of a possible role of DNA repair systems in ageing and neurodegenerative diseases after DNA damage is observed in the brain of individuals affected by neurodegenerative diseases. In the light of these findings, we investigated whether DNA repair gene polymorphisms (XRCC1 Arg399Gln, XRCC3 Thr241Met XPD Lys751Gln, XPG Asp1104His, APE1 Asp148Glu, and HOGG1 Ser326Cys) account for an increased risk of Parkinsons disease (PD). METHODS The present analyses are based on 60 case subjects with PD and 108 unrelated healthy controls. Genotyping of DNA repair gene polymorphisms were detected by polymerase chain reaction-restriction fragment length polymorphism. RESULTS We, for the first time, demonstrated the positive association of APE1, XRCC1, and XRCC3 DNA repair gene variants with PD risk. In our study, the frequencies of Glu/Glu genotype in APE1, Gln+ genotype of XRCC1, and Thr+ genotype of XRCC3 are higher in patients than in controls (p=0.028, p=0.002 and p=0.046, respectively). CONCLUSIONS In conclusion, our findings have suggested that APE1, XRCC1, and XRCC3 genetic variants may be a risk factor by increasing oxidative stress that might cause the loss of dopaminergic cells in the substantiata nigra and locus caeruleus, leading to abnormal signal transmittion, and ultimately, the development of PD. In addition, generation of reactive oxygen species from dopamine might affect the other DNA repair pathway proteins that we did not examine in the current study. Further studies with larger sample groups are necessary to clarify the role of DNA repair genes and the development of PD.

Effect of the methylenetetrahydrofolate reductase gene polymorphisms on homocysteine, folate and vitamin B12 in patients with bipolar disorder and relatives

We investigated the effect of polymorphic variants of c.1298A>C (Glu429Ala) and c.677C>T (Ala222Val) in methylenetetrahydrofolate (MTHFR) gene on the total homocysteine (tHcy), folate and B12 levels in patients with bipolar disorder, first-degree relatives of patients, and controls. The c.677C>T and c.1298A>C polymorphisms in MTHFR were determined by polymerase chain reaction-restriction fragment length polymorphism in 197 bipolar patients, 278 relatives and 238 controls. tHcy and folate and vitamin B12 levels were measured by Fluorescence Polarization Immunoassay and Electrochemiluminescence, respectively. The tHcy was significantly increased in patients and relatives. In contrast, folate and B12 were significantly lower in patients and relatives. Gender was not considered as a significant determinant in the multivariate analysis. Genotypes of c.1298A>C and c.677C>T were correlated with tHcy, folate and B12. Patients and relatives carrying TT and/or AA and AC genotypes had elevated tHcy and reduced folate and B12 levels. High tHcy but low folate and vitamin B12 levels may be a risk factor for development of bipolar disorder.

Combined effects of ACE and MMP‐3 polymorphisms on migraine development

Migraine is a primary headache disorder which involves both genetic and environmental components. Since angiotensin-converting enzyme (ACE) and matrix metalloproteinase (MMP) share the same homology, we investigated whether the MMP-3 and ACE I/D gene variants are involved in migraine risk and whether the ACE variant might act in combination with the MMP-3 genetic variant in patients with migraine. This is the first study to evaluate the association between MMP-3 and ACE polymorphisms, and migraine. Genotypes were determined by polymerase chain reaction. The frequencies of 5A5A genotypes of the MMP-3 and D allele of ACE were significantly elevated, but II genotypes of the ACE and 6A allele of MMP-3 significantly decreased in all patients. The combined DD/5A5A and ID/5A5A genotypes increased the risk of migraine. Individuals who were homozygous for the deletion (D) allele showed increased ACE activity. Subjects with the 5A5A genotype and/or D allele or with the combined DD/5A5A or ID/5A5A might be more susceptible to migraine development. In contrast, subjects with the II and/or 6A6A genotypes may be protected from migraine development. The greater activity of the 5A5A and DD genotypes might result in vascular reactivity that is more pronounced in migraine. Taken together, our data suggest that numerous genes may influence ACE activity. Discovery of new genes might better clarify the pathogenesis of migraine and open an avenue to therapeutic strategies against migraine.

PON1 55/192 polymorphism, oxidative stress, type, prognosis and severity of stroke.

We investigated the association of PON1 55/192 polymorphisms with type, severity and prognosis of stroke and oxidative markers. Paraoxonase1 (PON1), Glutathione Reductase (GSH‐Rd) and Malondialdehyde (MDA) levels were measured at day 1 and at day 5 following the onset of stroke. Genotypes were determined by polymerase chain reaction and restriction digestion. The frequencies of QQ and MM genotypes of PON1 192 and PON1 55, respectively, were significantly higher in controls than in patients. However, the allele frequencies of PON1 192 R and PON1 55 L were significantly more frequent in patients compared to controls. The frequency of combined genotype of RR/LL was significantly higher in cardioembolic group than in atherothrombotic group. PON1 activities were significantly diminished in stroke patients compared to controls. In contrast, serum MDA levels were significantly greater in patients than the values in controls. GSH‐Rd activity was higher in patients with small lesion and good prognosis than those with large and poor prognosis. Low density lipoprotein (LDL) levels in patients with large lesions were higher than those with small lesions. PON1 55/192 polymorphisms influence activity of the enzyme. PON1 55/192 genotypes have been associated with MDA levels. In conclusion, PON1 genetic variations are associated with risk factors, severity, type and prognosis of stroke and oxidative stress. IUBMB Life, 58: 165 ‐ 172, 2006

Angiotensin-converting enzyme polymorphism in schizophrenia, bipolar disorders, and their first-degree relatives.

Background Family, twin and adoption studies have provided major evidence for the role of genetics in numerous psychiatric disorders including schizophrenia (SZ) and bipolar disorders (BDs). As SZ and BD have some susceptibility genes in common and since unaffected first-degree relatives of these patients carry a high likelihood of these susceptibility genes, we aimed to elucidate the role of angiotensin-converting enzyme (ACE) genetic variants in patients with SZ, BD and their first-degree relatives. Methods The study sample comprised 239 patients with SZ, 184 patients with BD, 284 unaffected first-degree biological relatives of patients with SZ and 301 unaffected first-degree biological relatives of patients with BD and 210 healthy controls. The ACE genotypes were determined by polymerase chain reaction. Results ACE insertion/deletion polymorphism was associated with SZ and BD. DD genotype and D allele distributions in bipolar patients and their first-degree relatives were significantly higher than those of SZ patients, their relatives, and controls. In contrast, II genotype and I allele were reduced in both the patient groups and their relatives as compared with controls. Conclusion In this study, the D allele might be responsible for clustering of psychotic symptoms and results in the psychotic manifestations of BD, whereas I allele seems to be protective against development of SZ and BD. SZ and BD characterized by similar or different gene variant in ACE could be a useful marker for these psychiatric disorders, if this polymorphism is replicated in the future studies.

Association of genetic variants in Methylenetetrahydrofolate Reductase and Paraoxonase-1 genes with homocysteine, folate and vitamin B12 in coronary artery disease

Background The aim of the present study was to investigate the association between genetic variants in metylenetetrahydrofolate reductase (MTHFR) and Paraoxonase-1 (PON1) 55/192 genes and total homocysteine (tHcy), folate, B12 vitamin, and PON1 levels in patients with coronary artery disease (CAD). Methods The study included 235 patients with CAD and 268 healthy control subjects. Results LL and LM genotypes and L allele of PON1 55 were over-represented in patients. In contrast, MM genotype and M allele were more frequent in controls. QQ genotype and Q allele of PON1 192 and CT genotype of MTHFR were significantly diminished and QR genotype and R allele were significantly elevated in CAD patients compared with controls. The plasma tHcy were elevated but B12 levels were diminished in patients. PON1 55 and 192 genetic variants were significantly associated with PON1 activity, triglyceride, total cholesterol, tHcy and, high-density lipoprotein-cholesterol and low-density lipoprotein-cholesterol in patients, respectively. Conclusion Genetic variants of PON1 55/192 and MTHFR were associated with CAD.

Influences of genetic variants in interleukin-15 gene and serum interleukin-15 levels on coronary heart disease

Interleukin-15 (IL-15) is a potent proinflammatory cytokine that is now considered a key component of atherosclerosis. Proinflammatory gene polymorphisms lead to variations in the production and level of the proteins. In light of these findings, we hypothesized that variations in the gene coding for IL-15 influence the risk of coronary heart disease (CHD) by modulating the IL-15 levels. To test this hypothesis, we examined 5 single nucleotide polymorphisms (SNPs) in IL-15 gene and IL-15 levels in 102 patients with acute coronary syndrome (ACS), 102 patients with chronic ischemic stable CHD and 162 healthy control subjects. This study is the first report showing the influences of IL-15 gene variants and IL-15 levels on CHD. The five single nucleotide polymorphisms (SNPs) within the IL-15 gene, G367A, C267T, A14035T, C13687A, and A10504G were carried out by polymerase chain reaction/restriction fragment length polymorphism (PCR/RFLP). Serum IL-15 levels were significantly higher in both acute and chronic patients than in controls. Genetic variants of IL-15 gene and IL-15 levels were associated with CHD. In conclusion, our study supports the hypothesis that genetic variation in IL-15 gene and IL-15 levels influence the risk of CHD. Further studies are needed to confirm our hypothesis.

Paraoxonase-1 55/192 genotypes in schizophrenic patients and their relatives in Turkish population.

Background Oxidative stress and free radical-induced toxicity have been implicated in the pathophysiology of schizophrenia. In this study, we examined paraoxonase (PON1)-55/192 polymorphisms and PON1 activity in patients with schizophrenia, first-degree relatives of schizophrenic patients, and healthy controls. Methods This study consisted of 292 healthy participants, 267 unrelated patients with schizophrenia and 311 first-degree relatives of schizophrenic patients. PON1 55 (rs 854560) and PON1 192 (rs 662) polymorphisms were performed by restriction fragment length polymorphism. Results The frequencies of the QQ and LL genotypes were significantly overpresented in controls compared with those of schizophrenic patients and their relatives. In contrast, the RR genotype was more prevalent in patients than their relatives and healthy controls. The frequencies of the LM and QR genotypes in relatives were higher than controls. Serum PON1 activities of controls were significantly higher when compared with both schizophrenic patients and their relatives. The RR and LL genotypes were associated with a significantly increased PON1 activity as compared with QR or QQ and MM or LM genotypes, respectively, in all groups. Conclusion This is the first study that shows the association between PON1-55/192 polymorphisms and schizophrenia. Our data suggest that the subjects carrying R allele or RR genotype might be susceptible to schizophrenia and subjects with QQ or LL might be protected against schizophrenia. First-degree relatives of schizophrenic patients have higher heterozygote genotypes, suggesting that this group can shift either to patient or control group depending on their allele types and environmental factors. PON1 genetic variations are also associated with PON1 activities. Reduced PON1 activity in patients and their relatives might result from the combined effects of more than one polymorphic variant in PON1 or other genes and/or increased oxidative stress, supporting the hypothesis that reactive oxygen species-mediated cellular damage might contribute to the neuropathology of schizophrenia.

Homocysteine and pro-inflammatory cytokine concentrations in acute heart disease

Inflammation is involved in development and progression of atherosclerosis. Interleukin-2 (IL-2) and interleukin-6 (IL-6) have been correlated with various cardiovascular diseases. Hyperhomocysteinemia is an important risk factor for atherosclerosis and thrombotic disease. Recent studies have demonstrated that homocysteine (Hcy) enhances productions of several pro-inflammatory cytokines. In the light of these findings, we decided to determine if any relationship exists between IL-2 and IL-6, the pro-inflammatory cytokines, and total homocysteine (tHcy) in acute coronary syndrome (ACS). A total of 102 patients with ACS and 90 healthy subjects were included in the study. The levels of tHcy, IL-2 and IL-6 were higher and folic acid was lower in patients as compared with those of controls. Furthermore, data of the area under ROC plot for IL-2 demonstrated that IL-2 had higher sensitivity. These data suggest that enhanced inflammation may be associated with tHcy-related cardiovascular disease.