Anna Zdzienicka

Nitric Oxide Induces the Synthesis of Vascular Endothelial Growth Factor by Rat Vascular Smooth Muscle Cells

Vascular endothelial growth factor (VEGF) is known to induce the release of nitric oxide (NO) from endothelial cells. However, the effect of NO on VEGF synthesis is not clear. Accordingly, the effect of endogenous and exogenous NO on VEGF synthesis by rat vascular smooth muscle cells (VSMCs) was investigated. Two in vitro models were used: (1) VSMCs stimulated to produce NO by treatment with interleukin (IL)-1beta (10 ng/mL) and (2) VSMCs lipotransfected with pKecNOS plasmid, containing the endothelial constitutive NO synthase (ecNOS) cDNA. The synthesis of NO was inhibited by N(omega)-nitro-L-arginine methyl ester (L-NAME, 2 to 5 mmol/L) or diaminohydroxypyrimidine (DAHP, 2.5 to 5 mmol/L), inhibitors of NOS and GTP cyclohydrolase I, respectively. Some cells treated with L-NAME or DAHP were supplemented with L-arginine (10 mmol/L) or tetrahydrobiopterin (BH(4); 100 micromol/L), respectively. In addition, we studied the effect of sodium nitroprusside (SNP; 10 and 100 micromol/L) and chemically related compounds, potassium ferrocyanide and ferricyanide, on VEGF generation. IL-1beta induced iNOS expression and NO generation and significantly upregulated VEGF mRNA expression and protein synthesis. L-NAME and DAHP totally inhibited NO generation and decreased the IL-1beta-upregulated VEGF synthesis by 30% to 40%. Supplementation with L-arginine or BH(4) increased NO generation by L-NAME- or DAHP-treated cells, and VEGF synthesis was augmented by addition of BH(4). The cells generating NO after pKecNOS transfection released significantly higher amounts of VEGF than cells transfected with control plasmids. Inhibition of NO generation by L-NAME decreased VEGF synthesis. In contrast to the effect of endogenous NO, we observed the inhibition of VEGF synthesis in the presence of high (10 or 100 micromol/L) concentrations of SNP. This effect was mimicked by chemically related ferricyanide and ferrocyanide compounds, suggesting that the inhibitory effect of sodium nitroprusside may be mediated by an NO-independent mechanism. The results indicate that endogenous NO enhances VEGF synthesis. The positive interaction between endogenous NO and VEGF may have implications for endothelial regeneration after balloon angioplasty and for angiogenesis.

Dexamethasone Inhibits TNF-α Synthesis More Effectively in Alzheimer’s Disease Patients than in Healthy Individuals

Inflammatory mechanisms are involved in the pathogenesis of Alzheimer’s disease (AD). It is postulated that cytokine synthesis is altered in AD patients compared with nondemented subjects. Glucocorticoids play an important role in cytokine synthesis. We assessed the release of tumor necrosis factor-alpha (TNF-α), interleukin-10 (IL-10) and interleukin-12 (IL-12) and its regulation by dexamethasone in AD patients in vitro. Cytokine levels were measured using the ELISA method in unstimulated, LPS-stimulated or whole-blood samples incubated with LPS and dexamethasone from 18 AD patients and 12 controls. The cytokine levels spontaneously produced by blood cells after incubation with LPS or LPS and dexamethasone did not differ significantly between groups. Dexamathasone inhibited TNF-α synthesis by LPS-stimulated blood cells more effectively in AD patients than in controls. These results suggest that cytokine synthesis in AD patients could be regulated by glucocorticoids in a different way than in nondemented subjects.

Circulating N-terminal brain natriuretic peptide precursor and endothelin levels in patients with syndrome X and left bundle branch block with preserved systolic function

BACKGROUND Deterioration of left ventricular function during follow-up was reported in some patients with syndrome X and concomitant left bundle branch block. The patients with syndrome X and left bundle branch block has been frequently presented with elevated Endothelin-1 (ET-1) level while brain natriuretic peptide (BNP) (a sensitive marker of left ventricular dysfunction) has not been measured in patients with syndrome X. METHODS The purpose of the present study was to assess left ventricular diastolic function, levels of N-terminal Brain Natriuretic Peptide (NT-proBNP) precursor and biochemical parameters of endothelial function in patients with syndrome X complicated by left bundle branch block but preserved left ventricular systolic function (group A, n=8). The echocardiographic and neurohormonal measures in these patients were compared to those in patients with syndrome X without left bundle branch block (group B, n=13), and controls (group C, n=15). RESULTS At rest and after exercise the serum concentration of NT-proBNP was significantly higher in group A than in the controls (at rest: 232+/-96 vs. 133+/-23 fmol/ml, P=0.03; after exercise: 313+/-96 vs. 180+/-33 fmol/ml, P=0.02). The highest concentration of endothelin-1 was also found in group A, being significantly higher than in the controls (6.81 vs. 4.52 pg/ml, P<0.05). Mitral flow abnormalities were detected in left bundle branch block patients. Accordingly, the lowest E/A ratio was in group A and it differed significantly from that in group C (0.85 vs. 1.1, P<0.05). E/A ratio inversely correlated with plasma NT-proBNP concentration in patients with left bundle branch block (r=-0.48, P=0.02). CONCLUSIONS Elevated NT-proBNP and endothelin-1 plasma concentrations were demonstrated in patients with syndrome X complicated by left bundle branch block even when left ventricular systolic function was still preserved. In this subgroup the magnitude of left ventricular diastolic dysfunction correlated with the increase of BNP level which reflects neurohormonal activation.

Evaluation of genetic predisposition to insulin resistance by nutrient-induced insulin output ratio (NIOR).

Abstract Background: New tools to identify genotype-phenotype interactions need to be described and implemented. The aim of this study was to identify correlation between the risk originating from gene variation and diet-dependent development of insulin resistance. Methods: Insulin output in terms of area under the curve after an oral glucose tolerance test (AUC Ins OGTT) and lipid tolerance tests (AUC Ins OLTT) were measured in 167 overweight/obese patients. Estimation of the 18 common gene polymorphisms for obesity risk and standard phenotyping were performed. Results: Insulin output (AUC Ins OGTT) correlated strongly between both insulin treatments across the whole group. However, within the genotype sub-groups, correlation was lower or did not exist. Using a nutrient-induced insulin output ratio (NIOR), calculated as AUC Ins OLTT/AUC Ins OGTT, values ranged from 0.42 to 5.83 and correlated significantly with body mass index (BMI) and leptin, but not with age, gender, waist-to-hip ratio (WHR) and homeostasis model assessment of insulin resistance (HOMA-IR) or plasma adiponectin. High NIOR was found in a subgroup of carriers of rare allelic variants of genes characteristic for poorer tolerance to lipids in the diet. Low NIOR values were found within a sub-group with rare genetic variants regulating carbohydrate metabolism. Thus, the new insulin index NIOR may distinguish gene variant carriers into groups of glucose- or lipid-sensitive phenotypes. Conclusions: We suggest that the OLTT/OGTT insulin output ratio (NIOR) may be predictive for identifying individuals who are phenotypically susceptible to insulin resistance in response to high fat or carbohydrate in their habitual diet. Clin Chem Lab Med 2007;45:1124–32.

Trends and dynamics of changes in aortic pulse wave velocity over one-year observation period in patients treated with peritoneal dialysis.

important co-morbid condition affecting patients with chronic renal failure (1). There is an increasing body of evidence suggesting that mortality on dialysis largely depends upon initial and follow-up serum levels of proinflammatory cytokines and acute phase proteins (2, 3). Chronic inflammation is closely associated with atherosclerosis, which to a cer tain extent may be considered an inflammatory disease (4). Aortic pulse wave velocity (AoPWV) assessment proved its cl inical usefulness in patients with chronic renal disease, including those on maintenance hemodialysis (5-9). For uncertain reasons this problem was seldom studied in peritoneal dialysis (PD) patients. The aim of the present study was to assess the trends and dynamics of changes in AoPWV in the group of stable PD patients over one year and to search for possible correlations between these changes and one-year profile of selected cytokines, acute phase proteins and other variables that may be considered as risk factors for atherosclerosis progression. Forty seven patients (25M, 22F, aged mean 52.7 ± 12.8 years and on dialysis for 19.1 ± 21.6 months) were analyzed. AoPWV was measured using an automatic device with two pressure transducers (TY-306; Fukuda Denshi) placed on the carotid and femoral arteries and connected to an automatic processor (Complior® Colson). AoPWV was assessed at baseline and after 12 months. In each patient an absolute difference in PWV between two mentioned time-points was calculated (∆AoPWV). Serum Interleukin 6 (IL-6) and Tumor Necrosis Factor alpha (TNFα) were analyzed as proinflammatory cytokines (ELISA; Quantikine, R&D Systems), and C-reactive protein (high sensitive assay), lipoprotein (a) and fibrinogen – as acute phase reactants (immuno-nephelometry; Dade Boehring). In all patients total, LDL-, HDL-cholesterol and triglyceride serum levels, as well as serum calcium and phosphate were measured (Hitachi 917). All biochemical and inflammatory parameters were assessed at baseline, and after 6 and 12 months. At the end of the study mean concentrations of all analyzed biochemical parameters from three assessments was calculated. Blood pressure was measured at baseline, after 6 and 12 months, and mean arterial pressure (MAP) as well as pulse pressure (PP) were calculated. Mean AoPWV did not change significantly for the whole study group after one year (from 11.2 ± 2.26 to 11.7 ± 2.4 m/s, p= 0.07; ∆AoPWV +0.48 ± 1.77 m/s). However, in the population studied two categories of patients might be distinguished: subjects who progressed in AoPWV (29 patients, 61.7%, from 10.6 ± 2.3 to 12.3 ± 2.65 m/s; p< 0.05; ∆AoPWV +1.6 ± 1.14) and those with regression after 12 months (18 patients, 38%, from 12.2 ± 1.89 to 10.8 ± 1.67 m/s; p< 0.05; ∆AoPWV -1.31 ± 0.89). The entire group ‘averaged’ in terms of AoPWV value after 12 months, as the differences between “Pregressors” and “Regressors” were significant at the study commencement (p< 0.01) and only borderline significant (p= 0.08) at its completion. Patients who progressed were character ized by significantly higher values of mean serum phosphates, TNFα and Lp (a) levels as well as mean PP calculated from three assessments in comparison to “Regressors” (p< 0.05 for all differences). No significant difference was found between groups in terms of age, PD duration, and Short Communication The International Journal of Artificial Organs / Vol. 27 / no. 10, 2004/ pp. 904-906

EVALUATION OF GENETIC PREDISPOSITION TO INSULIN RESISTANCE BY NUTRIENT-INDUCED INSULIN OUTPUT RATIO (NIOR)

BACKGROUND New tools to identify genotype-phenotype interactions need to be described and implemented. The aim of this study was to identify correlation between the risk originating from gene variation and diet-dependent development of insulin resistance. METHODS Insulin output in terms of area under the curve after an oral glucose tolerance test (AUC Ins OGTT) and lipid tolerance tests (AUC Ins OLTT) were measured in 167 overweight/obese patients. Estimation of the 18 common gene polymorphisms for obesity risk and standard phenotyping were performed. RESULTS Insulin output (AUC Ins OGTT) correlated strongly between both insulin treatments across the whole group. However, within the genotype sub-groups, correlation was lower or did not exist. Using a nutrient-induced insulin output ratio (NIOR), calculated as AUC Ins OLTT/AUC Ins OGTT, values ranged from 0.42 to 5.83 and correlated significantly with body mass index (BMI) and leptin, but not with age, gender, waist-to-hip ratio (WHR) and homeostasis model assessment of insulin resistance (HOMA-IR) or plasma adiponectin. High NIOR was found in a subgroup of carriers of rare allelic variants of genes characteristic for poorer tolerance to lipids in the diet. Low NIOR values were found within a sub-group with rare genetic variants regulating carbohydrate metabolism. Thus, the new insulin index NIOR may distinguish gene variant carriers into groups of glucose- or lipid-sensitive phenotypes. CONCLUSIONS We suggest that the OLTT/OGTT insulin output ratio (NIOR) may be predictive for identifying individuals who are phenotypically susceptible to insulin resistance in response to high fat or carbohydrate in their habitual diet.