Assessment of incretins in oral glucose and lipid tolerance tests may be indicative in the diagnosis of metabolic syndrome aggravation

Incretins stimulated by oral meals are claimed to be protective for the pancreatic beta cells, to increase insulin secretion, to inhibit glucagon release, slow gastric emptying (glucagon-like peptide-1) and suppress appetite. Recently it has however been suggested that glucagon-like peptide-1 (GLP-1) is putative early biomarker of metabolic consequences of the obesity associated proinflammatory state. The study was aimed to compare the release of incretins and some of early markers of inflammation at the fasting and postprandial period induced by functional oral glucose as well as lipid load in healthy controls and patients with metabolic syndrome (MS) to see if functional tests may be helpful in searching for the inflammatory status of patients. Fifty patients with MS and 20 healthy volunteers (C) participated in this study. The 3-hour oral glucose (OGTT) and the 8-hour oral lipid (OLTT) tolerance tests were performed. At fasting leptin and adiponectin, as well as every 30 minutes of OGTT and every 2 hours of OLTT blood concentration of GLP-1, glucose-dependent insulinotropic polypeptide (GIP), glucose, insulin, triglycerides, free fatty acids, glutathione peroxidase, interleukin-6, sE-selectin, monocyte chemoattractant protein-1 (MCP1) and visfatin were measured. At fasting and during both OGTT and OLTT the level of incretins did not differ between the MS and the C group. Both glucose and lipids reach food activated incretins secretion. Glucose was the main GLP-1 release activator, while the lipid load activated evidently GIP secretion. A significantly larger AUC-GIP after the lipid-rich meal over the carbohydrate meal was observed, while statistically bigger value of AUC-GLP-1 was noticed in OGTT than in OLTT (P < 0.001) within each of the investigated groups. In patients with the highest fasting plasma GIP concentration (3(rd) tertile), IL-6, MCP-1, sE-selectin and visfatin blood levels were increased and correlated with glutathione peroxydase, leptin/adiponectin ratio, higher visfatin and interleukin-6 levels. The fat containing meals stimulate the long-lasting release of incretins, mainly GIP, parallel to the increase of the markers of low grade inflammation associating obesity in metabolic syndrome. The possibility of use of the postprandial (OLTT) GIP release measurement for the low grade inflammation progress in MS patients is suggested.

An association between aortic pulse wave velocity, blood pressure and chronic inflammation in ESRD patients on peritoneal dialysis

Increased aortic pulse wave velocity (AoPWV) has been identified as a risk factor for cardiovascular morbidity in the general population and in patients on dialysis. Most of the studies in ESRD patients refer to subjects on hemodialysis. Influence of the inflammatory process on aortic stiffening remains largely unknown. The aim of the present study was to evaluate potential relationships between AoPWV and blood pressure, basic anthropometric parameters, selected growth factors and markers of the inflammatory process in ESRD patients treated with peritoneal dialysis. The study population consisted of 43 patients (19 F, 24 M) with a mean age of 50.6 +/- 13.4 years on PD for a mean period of 21.9 +/- 20.7 months. AoPWV was measured using two pressure transducers placed on the carotid and femoral arteries and connected to an automatic processor (Complion Colson AS, Paris, France). Serum levels of Tumor Necrosis Factor alpha (TNFalpha), interleukin 6 (IL-6) and plasma basic Fibroblast Growth Factor (bFGF) were measured with ELISA; C-reactive protein and fibrinogen with nephelometry. Serum lipid profile was also assessed. Blood pressure was measured in an outpatient department under standardized conditions. Mean aortic pulse wave velocity in the study population was 10.7 +/- 2.1 m/s. No difference in AoPWV was found between men and women. AoPWV correlated significantly with age (R = 0.41; p < 0.01) but not with time on dialysis. Positive relationship between AoPWV and body weight and BMI was shown (R = 0.31; p < 0.05 and R = 0.35; p < 0.05, respectively). AoPWV correlated significantly with systolic blood pressure (SBP), mean arterial pressure (MAP) and pulse pressure (PP) (R = 0.46, p < 0.005, R = 0.46, p < 0.005 and R = 0.43, p < 0.01, respectively). AoPWV correlated with serum IL-6 and plasma bFGF (R = 0.32, p < 0.05 and R = 0.4, p < 0.01; respectively). The correlation with serum CRP was borderline significant (p < 0.53). In multiple regression analysis age (beta 0.38; p < 0.005), plasma bFGF level (beta 0.3; p < 0.05), and systolic blood pressure (beta 0.29; p < 0.05) were independently associated with pulse wave velocity. Our results suggest that AoPWV values in patients on PD are associated with factors similar to those encountered in the general population. We suggest that increased aortic stiffening may also be related to the chronic inflammatory process in PD patients.

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.

[Determination of melatonin concentrations in patients with consciousness disturbances after craniocerebral trauma. Preliminary communication]

The study was performed in cooperation of the Department of Neurotraumatology and the Department of Clinical Biochemistry Jagiellonian University in Cracow. In patients with central nervous system injury, diagnosed upon computerized tomography scan, melatonin levels were measured. The most frequent reason of damage was severe craniocerebral trauma. Consciousness, assessed according to Glasgow Coma Scale, was between 3 to 13 points. Melatonin levels were measured at 8 a.m. The investigation could not demonstrate any correlations between consciousness disturbances after head injury and serum melatonin levels in the morning. To draw a final conclusion further experiments are necessary. They will help to explain the role of endogenous melatonin in patients after craniocerebral injury.

Effects of comicronised fenofibrate on lipid and insulin sensitivity in patients with polymetabolic syndrome X

BACKGROUND

This study investigated the effects of comicronised fenofibrate in patients with dyslipidemia and polymetabolic syndrome X.

DESIGN

After a 6-week dietary run-in phase, 37 male patients eligible on lipid criteria entered a 12-week treatment phase consisting of diet plus one capsule daily containing 200 mg of comicronised fenofibrate (Lipanthyl(R)).

RESULTS

A significant reduction in plasma concentrations of total cholesterol, LDL cholesterol and triglyceride was observed after 4, 8 and 12 weeks of treatment with fenofibrate. The improvement in the atherogenic index LDL/HDL cholesterol from a pretreatment 3.8 to 3.0 after treatment was highly statistically significant and may be judged as satisfactory. Significant changes were also observed in haemostatic factors (fibrinogen reduced by 19%, factor VII activity reduced by 18%). Fasting serum insulin levels and insulin response (area under the curve) after oral glucose load were significantly reduced by 26.8% and 18.7%, respectively, indicating an improvement of insulin sensitivity. Systolic and diastolic blood pressure were significantly reduced. Uric acid was significantly reduced by 21.6%.

CONCLUSION

These favourable effects of comicronised fenofibrate both on lipid and non lipid parameters, including insulin sensitivity, may confer to this product a particular interest in the treatment of patients with polymetabolic syndrome X.

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.

[Daily excretion of epinephrine and norepinephrine in acute phase of cerebral ischemia]

The aim of the study was to assess the relation between urinary excretion of epinephrine and norepinephrine, and stroke severity, prognosis and standard biochemical investigations in acute phase of ischaemic stroke. The study was done on the material of 36 patients (17 women and 19 men, aged 41-89 years, mean: 69 +/- 13 years) admitted to the stroke unit of the Neurology Department within 24 hours (mean: 7.7 hours), after the first ever ischaemic stroke affecting the territory of the internal carotid artery circulation, confirmed by CT. Patients with the history of diabetes mellitus, cardiac insufficiency and infection on admission were excluded from the study. The 24-hour urine collection for catecholamines (epinephrine and norepinephrine) was done on the first and third day of hospitalization. An even single increased daily excretion of epinephrine (> 10 micrograms/24 hr) was found in 21 and norepinephrine (> 50 micrograms/24 hr) in 10 of 36 patients. No correlation between daily excretion of epinephrine and norepinephrine was found. Statistical analysis revealed a significant relation between norepinephrine, but not epinephrine, and neurological deficit, prognosis and some biochemical parameters of investigated patients. Patients with increased daily excretion of norepinephrine showed worse neurological deficit (p < 0.01), greater mortality assessed on the 30-th and 90-th day of stroke (p < 0.05) and increased plasma glucose, sedimentation rate, white blood cells count, creatinine kinase activity as well as microalbuminuria and decreased plasma kalium concentration.

Apo E isoforms, insulin output and plasma lipid levels in essential hypertension

BACKGROUND

The association between apo E isoforms and insulin output during the oral glucose test (OGTT) in 60 non-diabetic, non-obese patients with essential hypertension and in control subjects (non-obese, non-diabetic normotensive subjects) was estimated.

METHODS

According to low or high insulin output during OGTT, the subjects were divided into the following groups: normotensive subjects with low (NLI) and high (NHI) and hypertensive subjects with low (HLI) and high (HHI) insulin output.

RESULTS

The apo E 4/2 phenotype was detected in 32% of hypertensive subjects but not in control subjects. The frequency of apo E 3/2 phenotype in hypertensive subjects was 5% and in normotensive subjects 15%. An increased frequency of phenotype apo E 4/3 was noticed both in HHI (46%) and in NHI (50%) compared with HLI (22%) and NLI (17%) groups.

CONCLUSION

The results suggest that the determination of phenotypes apo E and insulin output may contribute to an early detection of individuals at high risk of hypertension development.

Heterogeneity of high-density lipoprotein particles and insulin output during oral glucose tolerance test in men with coronary artery disease

We compared the high-density lipoprotein (HDL) composition and particle heterogeneity in 60 nonobese (normal body mass index, BMI) men suffering from coronary artery disease (CAD) with normolipemia and normoinsulinemia with lower and higher insulin output during the oral glucose tolerance test (silent hyperinsulinemia). The apolipoprotein apoAI, apoAII, and apoE levels were higher in the high insulin response (HI) group than in low insulin response (LI) group. The ratio of apoAI versus total protein and the ratio of apoAI versus total cholesterol were increased in HI compared with LI. The lipid components in HDL were higher in LI than in HI, while for HDL2 they were higher in HI. The fractioning of HDL by gradient gel electrophoresis revealed a different pattern of HDL particles in both groups. The larger particles, HDL2b and HDL2a (mean particle diameters 10.6 and 9.2 nm, respectively), occur more frequently in HI patients (up to 60%) than in LI patients, whereas the smaller particles, HDL3a and HDL3b (mean particle diameters 8.6 and 7.8 nm, respectively), predominate in LI patients. Our results demonstrate that even in the normoglycemic, normocholesterolemic CAD patients, a high insulin output observed during the oral glucose tolerance test may be connected with a different HDL particle pattern, which suggests changes in the reverse cholesterol transport.

Relation between insulinaemia and lipoprotein composition in men with primary arterial hypertension with and without hypertriglyceridaemia

The purpose of the study was to evaluate a relationship between HDL, triglyceride levels and insulinaemia in primary arterial hypertension. The study population consisted of 60 men aged 32-68 years (mean age 50.87 years, s.d. 8.4) with hypertension duration of 11.1 years (s.d. 6.4 years) who were compared with 60 normotensives matched for sex, age and BMI. We examined blood pressure, plasma lipoprotein content, sum of glucose and sum of insulinaemia (sum ins) during OGTT (oral glucose tolerance test). OGTT revealed insulin secretion almost twice as high in hypertensives (P < 0.001 sum ins 11002 microU min/ml, s.d. 4846) than in normotensives (sum ins 6662 microU min/ml, s.d. 3099). Comparison of concentration of selected VLDL components shows that hypertensives were characterised by markedly higher concentration of triglycerides (1.46 mmol/L, s.d. 0.87 in hypertensives and 1.04 mmol/L, s.d. 0.54 in normotensives), free and esterified cholesterol and protein, including apolipoprotein B than normotensives. It was also found that hypertensives had higher levels of apo CIII0 and lower levels of CIII1 VLDL than normotensives. Hypertensive patients showed also a higher frequency of apo E2 isoforms (three-fold) and apo E4 isoforms (two-fold) than healthy subjects. No changes were detected in the composition of LDL and HDL between the groups. Analysing the discriminating ability of biochemical parameters chosen in a step-wise manner it was found that sum ins and HDL, protein and cholesterol concentrations were the factors most powerfully differentiating men with hypertension from healthy subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

[Decrease in the level of free cholesterol fraction HDL as a risk factor for threatened atherosclerosis in idiopathic hyperinsulinemia]

Inversive association between concentration of plasma high density lipoprotein (HDL) components and endogenous insulin response to oral glucose uptake was observed in 89 healthy, normolipidaemic, non obese, non diabetic male subjects. Inversive correlation between sum of insulin released during oral glucose tolerance test and HDL free and esterified cholesterol as well as apolipoprotein A1 concentration were confirmed. Coexistence of increased insulin secretion and low ratio of free cholesterol concentration to esterified cholesterol and to proteins in HDL was also observed. In separate group of subjects with normal glucose tolerance in high insulin response subgroup the cholesterol (free and esterified) and protein concentrations were lower than in subgroup with low insulin response. The free cholesterol/esterified cholesterol and free cholesterol/protein (apoA1) ratios were decreased in high insulin response subgroup. It is concluded that low concentration of free cholesterol is a most significant change of HDL composition in hyperinsulinemic, healthy men.