Maria Olszewska

Plasma concentrations of TNF-α and its soluble receptors sTNFR1 and sTNFR2 in patients with coronary artery disease

Tumour necrosis factor alpha (TNF-alpha) is implicated in post-ischemic myocardial dysfunction. Two distinct TNF-alpha receptors are shed from cell membranes and circulate in plasma as soluble sTNFR1 and sTNFR2 proteins. The aim of the study was to establish factors associated with plasma concentrations of TNF-alpha and its receptors in patients with coronary artery disease (CAD). Since adenosine inhibits the expression of TNF-alpha, two functional polymorphisms in genes encoding enzymes participating in adenosine metabolism, i.e. AMP deaminase-1 (AMPD1, C34T) and adenosine deaminase (ADA, G22A), were analyzed. Plasma concentrations of TNF-alpha, sTNFR1, and sTNFR2 were measured using ELISA in 167 patients with CAD. Common factors significantly associated with higher TNF-alpha, sTNFR1, and sTNFR2 were lower glomerular filtration rate (GFR), older age, higher BNP, lower blood haemoglobin, and the presence of asthma or chronic obstructive pulmonary disease (COPD). Higher TNF-alpha and sTNFR1 concentrations were also associated with the presence of heart failure (HF), lower ejection and shortening fraction, the presence of diabetes or metabolic syndrome, lower serum HDL cholesterol, and higher uric acid. In multivariate analysis the common independent predictors of higher TNF-alpha, sTNFR1, and sTNFR2 were lower GFR, lower HDL cholesterol, higher BNP, and the presence of asthma or COPD. There were no associations between AMPD1 C34T or ADA G22A genotypes and TNF-alpha or its receptors. In conclusion, the concentrations of TNF-alpha, sTNFR1, and sTNFR2 reflect the impairment of cardiac and renal function in patients with CAD. Metabolic syndrome and diabetes are associated with higher plasma concentrations of TNF-alpha and its receptors.

Elements of Mediterranean diet improve oxidative status in blood of kidney graft recipients

Patients were fully informed as to the study objectives and benefits, and provided written consent prior to enrolment. The study protocol was approved by the Committee on Human Research at the Pomeranian Medical University, Szczecin, Poland. An intensification of free-radical reactions may contribute to accelerated atherosclerosis in kidney graft recipients. We examined the effect of a Mediterranean-type diet (MD) on the oxidative status of the plasma and erythrocytes of kidney graft recipients. Two patient groups were formed: a study group consuming the MD diet and a control group with a low-fat diet. C-reactive protein levels in plasma, oleic acid C18 : 1n-9 and linoleic acid C18 : 2n-6 concentrations in triacylglycerols were determined. To determine the oxidative status, we measured the concentrations of alpha-tocopherol in plasma, the content of thiobarbituric acid-reactive species (TBARS) in plasma and erythrocytes, and the activities of superoxide dismutase, catalase and glutathione peroxidase in erythrocytes. In the MD group, the activities of erythrocyte enzymes changed significantly: those of superoxide dismutase increased (P<0.001 after 6 months), catalase decreased (P<0.001 after 6 months) and glutathione peroxidase decreased (P<0.05 after 2 months). The oleic acid content of triacylglycerols was increased (P<0.006) whereas that of linoleic acid was decreased (P<0.00005), alpha-tocopherol levels remaining unchanged. TBARS in plasma were decreased after 6 months of MD (P<0.05). No significant correlations were observed between TBARS, oleic acid, linoleic acid and alpha-tocopherol levels in plasma. MD appears to protect the erythrocytes against the action of free radicals, as reflected in the modified activities of some enzymes regulating the oxidative status of these blood cells.

PIN1 gene variants in Alzheimer's disease

BackgroundPeptidyl-prolyl isomerase, NIMA-interacting 1 (PIN1) plays a significant role in the brain and is implicated in numerous cellular processes related to Alzheimers disease (AD) and other neurodegenerative conditions. There are confounding results concerning PIN1 activity in AD brains. Also PIN1 genetic variation was inconsistently associated with AD risk.MethodsWe performed analysis of coding and promoter regions of PIN1 in early- and late-onset AD and frontotemporal dementia (FTD) patients in comparison with healthy controls.ResultsAnalysis of eighteen PIN1 common polymorphisms and their haplotypes in EOAD, LOAD and FTD individuals in comparison with the control group did not reveal their contribution to disease risk.In six unrelated familial AD patients four novel PIN1 sequence variants were detected. c.58+64C>T substitution that was identified in three patients, was located in an alternative exon. In silico analysis suggested that this variant highly increases a potential affinity for a splicing factor and introduces two intronic splicing enhancers. In the peripheral leukocytes of one living patient carrying the variant, a 2.82 fold decrease in PIN1 expression was observed.ConclusionOur data does not support the role of PIN1 common polymorphisms as AD risk factor. However, we suggest that the identified rare sequence variants could be directly connected with AD pathology, influencing PIN1 splicing and/or expression.

Platelets arachidonic acid metabolism in patients with essential hypertension.

Arachidonic acids (AA) metabolites, eicosanoids, exert a tremendous influence on circulatory and vascular homeostasis, and in humans are generated by many organs and cell types. In this study we wanted to verify whether platelets AA metabolism play a significant role in pathogenesis of essential hypertension (EH). Participants were divided into the study (EH) and the control group. Plasma and urine concentrations of isoprostanes (8-iPF2α-III) and thromboxane B2 (TxB2) were determined using the ELISA method. The levels of 5- and 12-hydroxyeicosatetraenoic (HETE) acids, generated by platelets, were analysed using RP-HPLC. In a suspension of not stimulated and AA-stimulated platelets TxB2 level was statistically lower in the study than in the control group (p < 0.0001 and 0.001 respectively). The concentration of 12-HETE was significantly elevated in EH patients compared to the control group; however, only in the non-stimulated conditions (p < 0.05). Plasma and urine F2-isoprostanes levels were significantly higher in hypertensive individuals than in the control group (p < 0.00002 and p < 0.01 respectively). Moreover, EH patients excreted more TxB2 in urine than normotensive individuals (p < 0.05). Our results highlight the mutual connections between the platelets AA metabolism and indicate its possible role in the pathogenesis of arterial hypertension. Moreover, we hypothesize that platelets AA metabolism may exert a pro-atherosclerotic effect. Finally, we suggest the use of (5-HETE+12-HETE)/TxB2 parameter in further studies.

Microelements in Stones, Urine, and Hair of Stone Formers: A New Key to the Puzzle of Lithogenesis?

The role of trace elements in lithogenesis is still unclear. The aim of this study was to evaluate the levels of elements in urinary stones and in the urine and hair of stone formers to identify these elements that have synergic correlations in studied materials and may contribute to lithogenesis. A total of 219 consecutive patients with idiopathic upper urinary tract stones were prospectively enrolled in the study. Urine and hair samples were collected from all patients. The content of the stone was evaluated using atomic absorption spectrometry, spectrophotometry, and colorimetric methods. The analysis of 29 elements in stones and hair and 21 elements in urine was performed using inductively coupled plasma-atomic emission spectrometry. The strength of correlation was described with the value of Spearman’s rank correlation coefficient. The positive correlation between concentration of sodium, potassium, magnesium, barium, vanadium, zinc, silicon, phosphorus, and iodine in phosphate stones was observed. Only a few incidental correlations between the composition of stones and the distribution of elements in urine and in hair were found. There were 109 positive two-element correlations between two materials. The most common were observed for vanadium, aluminum, lead, cobalt, and molybdenum. Two-element positive correlations for all samples were established only for three elements: vanadium, lead, and aluminum. Results indicate that analysis of particular elements in hair and urine cannot predict the composition of urinary stones. This study showed, for the first time, correlations between the levels of vanadium, lead, and aluminum in the stones, urine, and hair of stone formers.

Association of C34T AMPD1 gene polymorphism with features of metabolic syndrome in patients with coronary artery disease or heart failure.

Objective. The common C34T polymorphism in the AMP deaminase‐1 (AMPD1) gene results in an inactive enzyme in homozygotes for the mutated T allele. Some studies have shown an association of T allele with longer survival in heart failure (HF) and/or coronary artery disease (CAD). The aim of this study was to assess genotype–phenotype correlations in such patients, with emphasis on components of the metabolic syndrome. Methods. Ninety‐seven patients with CAD without HF (CAD+ HF–) and 104 with HF (HF+) were genotyped by PCR‐RFLP. The genetic control group comprised 200 newborns. Results. No significant differences were found in the frequency of AMPD1 genotypes between the groups. In the CAD+ HF– group, the carriers of T allele compared to CC homozygotes had significantly lower values of waist circumference (89.5±8.5 versus 97.7±11.2 cm; p = 0.00029), waist/hip ratio (p = 0.0059) and BMI (p = 0.045). There was no diabetes or fasting glycaemia ⩾126 mg/dL in T carriers, while these features were present in 25 % of CC homozygotes (p = 0.0024). In the HF+ group, a tendency towards a lower prevalence of diabetes (20 % versus 41 %; p = 0.068) and significantly lower systolic blood pressure (p = 0.048) were observed in T allele carriers. Conclusions. C34T AMPD1 polymorphism may be associated with reduced frequency of obesity in CAD patients and of hyperglycaemia and diabetes in both CAD and HF patients. Morphometric parameters associated with adipose tissue distribution and parameters of glucose metabolism should be analysed as potential confounders in further studies on the role of polymorphisms of AMPD1 and other genes associated with AMP and adenosine metabolism in cardiovascular disease.

AMPD1 gene mutations are associated with obesity and diabetes in Polish patients with cardiovascular diseases

Previous studies showed an association of the common functional polymorphism (C34T, Gln12Stop) in the adenosine monophosphate deaminase-1 (AMPD1) gene with survival in heart failure (HF) and/or coronary artery disease (CAD). The aim of the study was to search for other mutations in selected regions of the AMPD1 gene in Polish CAD and HF patients, and to analyze their associations with obesity and diabetes. Exons 2, 3, 5, and 7 of AMPD1 were scanned for mutations in 97 patients with CAD without HF (CAD+ HF−), 104 patients with HF (HF+), and 200 newborns from North-Western Poland using denaturing high-performance liquid chromatography (DHPLC), polymerase chain reaction–restriction fragment length polymorphism (PCR-RFLP), and direct sequencing. Frequencies of AMPD1 C34T mutation, as well as novel A99G, G512A, IVS4-6delT, and C784T sequence alterations, were similar in the three groups, but 860T mutated allele was less frequent in the combined CAD+ HF− and HF+ groups than in the controls (1.7% vs. 4.3%, p = 0.040). Heterozygous 34CT genotype was associated with lower (odds ratio [OR] = 0.32, 95% confidence interval [CI] = 0.13–0.81) and 860AT with higher (OR = 13.7, 95%CI = 1.6–118) prevalence of diabetes or hyperglycemia in relation to wild-type homozygotes. Abdominal obesity was more frequent in 860AT patients than in wild-type homozygotes and 34CT heterozygotes (86% vs. 40% vs. 29%, p < 0.05). Nine genes containing polymorphisms linked with AMPD1 C34T mutation were found in the HapMap database. AMPD1 C34T nonsense mutation is associated with reduced prevalence of diabetes and obesity in patients with CAD or HF, but A860T substitution seems to exert opposite metabolic effects and should always be accounted for in the studies of the AMPD1 genotype.

Does smoking have any effect on urinary stone composition and the distribution of trace elements in urine and stones

The role of particular elements in lithogenesis is still unclear and debated. Probably some of them may promote or conversely inhibit crystal nucleation of organic or mineral species. A few epidemiological data link smoking with the risk of calcium stones. The aim of this hospital-based study was to evaluate the distribution of trace elements in urine and urinary stones, and possible correlation with stone constituents in smoking and non-smoking individuals. 209 stones and urine samples collected from idiopathic stone-formers were analyzed to evaluate the mineral composition and the distribution of elements, 29 in stones and 21 in urine. Values were statistically compared considering smoking, arterial hypertension and coronary heart disease as grouping variables. No differences were noted either for comparison of mineral components or the elements concentrations in stones in both groups. The concentration of mercury in urine was higher in smokers than in non-smokers, but the statistical significance was at the moderate level. Our findings do not support the concept of possible association between smoking and urinary lithogenesis, but we believe that further investigations are needed in this area.

Metformina – mechanizmy działania i zastosowanie w terapii cukrzycy typu 2[i][/i]

Metformin is widely used for the treatment of type 2 diabetes mellitus. Although this biguanide derivative has been used for more than 50 years, its mechanism of action has not been fully elucidated. In this article we describe the latest achievements concerning the mechanisms of antihyperglycemic action of metformin. They include: decrease of glucose absorption in the small intestine, increase of glucose transport into cells, decrease in the plasma free fatty acid concentrations and inhibition of gluconeogenesis. Activation of AMP-activated protein kinase (AMPK) plays an important role in these processes. The latest discoveries have revealed mechanisms of anti-atherosclerotic, hypotensive and anticancer action of metformin and its impact on vein endothelial function. The pleiotropic actions of metformin include impact on plasma lipid profile, decrease of oxidative stress, and increase in plasma fibrinolytic activity. Although metformin is not metabolized, the latest research has shown that it is actively transported into hepatocytes and renal tubular epithelium, by OCT1 (organic cation transporter 1, encoded by the SLC22A1 gene) and OCT2 (organic cation transporter 2, encoded by the SLC22A2 gene), respectively. However, MATE1 transporter (multidrug and toxin extrusion 1 protein) is encoded by the SLC47A1 gene and facilitates metformin excretion from these cells into bile and urine. Metformin transporter gene polymorphisms may contribute to significant variation in drug response. Further studies of mechanisms of metformin action could contribute to its wider use for the prevention of type 2 diabetes mellitus, cancer, and Alzheimer’s disease, and for the treatment of type 1 diabetes mellitus, and polycystic ovary syndrome (PCOS).

Does Glucose Present in the Dialysate Limit Oxidative Stress in Patients Undergoing Regular Hemodialysis

Background: Decreased glucose concentration in the blood causes the inhibition of the hexose monophosphate (HMP) cycle in the erythrocyte. NADPH, which is the source of the reductive equivalents necessary for the reproduction of glutathione (GSH), is not regenerated. The presence of glucose in dialysate should provide the stability of its concentration in the blood of patients undergoing hemodialysis (HD). The aim of the study was to assess the influence of glucose in the dialysate on the intensity of oxidative stress in patients undergoing regular HD. Methods: The study comprised 43 patients hemodialyzed with dialysate containing (HD-g(+)) or not containing glucose (HD-g(–)). The concentrations of the products of reaction with thiobarbituric acid-reactive substance (TBARS) and GSH as well as the activity of erythrocyte superoxide dismutase were determined. Glucose concentrations in the blood before and immediately after dialysis were also measured. Results: After flow-through dialysis the glucose concentration in the blood decreases both when dialysate does not contain glucose (4.8 vs. 1.6 mmol/l) and when dialysate contains glucose (6.6 vs. 5.8 mmol/l). HD caused changes in the TBARS concentration: in the HD-g(+) group the concentration decreased after HD, whereas in the HD-g(–) group it increased. In both groups of patients studied the GSH concentration changed after HD; in the HD-g(–) group it decreased and in the HD-g(+) group it increased. The results obtained in the groups of patients examined were confirmed by in vitro studies. Conclusions: The presence of glucose in the dialysate guarantees the normal activity of the HMP cycle, which provides the production of reductive equivalents for the regeneration of reduced GSH – free radicals scavenger – and therefore the limitation of oxidative stress.