Low N-terminal pro-brain natriuretic peptide levels are associated with non-alcoholic fatty liver disease in patients with type 2 diabetes.

AIM: Natriuretic peptides (NPs) have emerged as important regulators of lipid metabolism. Reduced levels of NPs are reported in obesity and in patients with type 2 diabetes (T2D). This NP deficiency may affect their ectopic fat distribution and lead to high risk of non-alcoholic fatty liver disease (NAFLD). METHODS: In this cross-sectional study, the association between N-terminal pro-B-type natriuretic peptide (NT-proBNP) and liver fat content was quantified using 1H-magnetic resonance spectroscopy in 120 patients with T2D. RESULTS: NAFLD (defined as liver fat content ≥ 5.6%) was found in 57 (48%) of the T2D patients, who also had significantly lower NT-proBNP (P = 0.002) levels compared with patients without NAFLD, but did not differ as regards the presence of cardiovascular disease (CVD) or in kidney function. After adjusting for potential confounders (age, gender, HbA1c, BMI, HOMA2-IR, CVD, eGFR), the odds ratio for the presence of NAFLD was increased by 2.9 (P = 0.048) for NT-proBNP levels < 45 ng/L. In a multivariable linear regression model, the relationship with NT-proBNP was further analyzed as a continuous variable, and was independently and inversely associated with increasing liver fat content after full adjustment (P = 0.031). CONCLUSION: Reduced plasma NT-proBNP levels are independently associated with high liver fat content in patients with T2D. The present study suggests that NP deficiency may play a role in the development of NAFLD in T2D.

Association between left ventricular global longitudinal strain and natriuretic peptides in outpatients with chronic systolic heart failure.

BACKGROUND: Both impaired left ventricular (LV) global longitudinal strain (GLS) and increased plasma concentrations of natriuretic peptides(NP) are associated with a poor outcome in heart failure (HF). Increased levels of NP reflect increased wall stress of the LV. However, little is known about the relationship between LV GLS and NP. This aim of this study was to evaluate the relationship between the echocardiographic measure LV GLS and plasma levels of NP. METHODS: We prospectively included 149 patients with verified systolic HF at the baseline visit in an outpatient HF clinic. LV GLS was assessed by two dimension speckle tracking and plasma concentrations of N-terminal-pro-brain-natriuretic-peptide (NT-proBNP) and pro-atrial-natriuretic-peptide (proANP) were analysed. RESULTS: The patients had a median age of 70 years, 28.2 % were females, 26.5 % were in functional class III-IV, median left ventricular ejection fraction (LVEF) was 33 % and median LV GLS was -11 %. LV GLS was associated with increased plasma concentrations of NT-proBNP and proANP in multivariate logistic regression (NT-proBNP: Odds RatioGLS: 7.25, 95 %-CI: 2.48-21.1, P < 0.001 and proANP: Odds RatioGLS: 3.26, 95-%-CI: 1.28-8.30, P = 0.013) and linear regression (NT-proBNP: ßGLS: 1.19, 95 %-CI: 0.62-1.76, P < 0.001 and proANP: ßGLS: 0.42, 95-%-CI: 0.11-0.72, P = 0.007) models after adjustment for traditional confounders (age, gender, body-mass-index, atrial fibrillation, renal function) and left atrial volume index. CONCLUSION: Impaired LV GLS is associated with increased plasma concentrations of NP and our data suggest that left ventricular myocardial mechanics estimated by LV GLS reflects myocardial wall stress in chronic systolic HF.

Investigating the causal effect of vitamin D on serum adiponectin using a Mendelian randomization approach.

BACKGROUND/OBJECTIVES: The aim was to examine the causal effect of vitamin D on serum adiponectin using a multiple instrument Mendelian randomization approach. SUBJECTS/METHODS: Serum 25-hydroxy vitamin D (25(OH)D) and serum total or high molecular weight (HMW) adiponectin were measured in two Danish population-based studies: the Inter99 study (6405 adults, 30-60 years) conducted in 1999-2001, and the MONICA10 study (2656 adults, 41-71 years) conducted in 1993-1994. RESULTS: In the Inter99 study, serum 25(OH)D was positively associated with total adiponectin (the effect estimate in % per doubling of 25(OH)D was 4.78, 95% CI: 1.96, 7.68, P<0.001). Using variations in the vitamin D-binding protein gene and the filaggrin gene as instrumental variables, the causal effect in % was estimated to 61.46, 95% CI: 17.51, 120.28, P=0.003 higher adiponectin per doubling of 25(OH)D. In the MONICA10 cohort, no significant association was observed between the serum concentrations of 25(OH)D and HMW adiponectin (the effect estimate in % per doubling of 25(OH)D was -1.51, 95% CI: -5.80, 2.98, P=0.50), although the instrumental variables analysis to some extent supported a positive causal association (the effect estimate in % per doubling of 25(OH)D was 37.13, 95% CI: -3.67, 95.20, P=0.080). CONCLUSIONS: The results indicate a possible causal association between serum 25(OH)D and total adiponectin. However, the association was not replicated for HMW adiponectin. Thus, further studies are needed to confirm a causal relationship.

Abnormal glucose metabolism is associated with reduced left ventricular contractile reserve and exercise intolerance in patients with chronic heart failure.

AIMS: To investigate the associations between glucose metabolism, left ventricular (LV) contractile reserve, and exercise capacity in patients with chronic systolic heart failure (HF). METHODS AND RESULTS: From an outpatient HF clinic, 161 patients with systolic HF were included (mean age 70 ± 10 years, 69% male, 59% had ischaemic heart disease, mean LV ejection fraction (LVEF) 37 ± 9%). Thirty-four (21%) patients had known diabetes mellitus (DM). Oral glucose tolerance testing (OGTT) classified patients without a prior DM diagnosis as normal glucose tolerance (NGT), impaired glucose tolerance or new DM. All patients completed low-dose dobutamine echocardiography (LDDE) and 154 patients a 6-min walking distance test (6MWD). Compared with patients with NGT, patients with known DM had lower resting LVEF (33.4 vs. 39.1%, P < 0.05) and higher E/e' (13.9 vs. 11.4, P < 0.05). During LDDE, an increase in LVEF could be observed in all glycemic groups (mean 8.2% absolute increase), but the contractile reserve was lower in patients with known DM (-5.4%, P = 0.001) and new DM (-3.5%, P = 0.035) compared to patients with NGT. 6MWD was lower in known DM (349 m) and new DM (379 m) compared with NGT (467 m) (P < 0.001). Differences in clinical variables, resting echocardiographic parameters or contractile reserve, did not explain the exercise intolerance related to diabetes. CONCLUSION: Diabetes, known or newly detected by OGTT, is independently associated with reduced LV contractile reserve and exercise intolerance in outpatients with systolic HF. These findings may offer one explanation for the excess mortality related to diabetes in HF.

Cardiovascular events in thyroid disease: a population based, prospective study.

No consensus exists whether subclinical thyroid disease should be treated or just observed. Untreated overt thyroid disease is associated with increased risk of cardiovascular disease, and this study was conducted to assess the risk of cardiovascular events in subclinical thyroid disease. The population-based prospective study was conducted in Denmark. A total of 609 subjects from general practice aged 50 years or above with normal left ventricular function were examined. During a median of 5 years of follow-up, major cardiovascular events were documented. In subjects with abnormal TSH at baseline, information about potential thyroid treatment during follow-up was obtained from case reports and mailings. At baseline, 549 (90.7%) were euthyroid (TSH 0.40-4.00 mU/l), 31 (5.1%) were subclinical hypothyroid (TSH>4.00 mU/l), and 25 (4.1%) were subclinical hyperthyroid (TSH<0.40 mU/l). 1 overt hyperthyroid and 3 overt hypothyroid participants were excluded from the analyses. At baseline, the levels of NT-proBNP were inversely associated with the levels of TSH; the lower the levels of TSH, the higher the NT-proBNP concentration. During follow-up, 88 participants died, 81 had a major cardiovascular event, and 28 had a stroke. The incidence of stroke was increased among subjects with subclinical hyperthyroidism, HR 3.39 (95% CI 1.15-10.00, p=0.027) after adjusting for sex, age, and atrial fibrillation. Subclinical hypothyroidism was not related with any of the outcome measurements. Subclinical hyperthyroidism seems to be a risk factor of developing major cardiovascular events, especially stroke in older adults from the general population with normal left ventricular function.

N-terminal-pro-B-type natriuretic peptide during pharmacological heart rate reduction in hyperthyroidism.

We hypothesized that elevated N-terminal-pro-B-type natriuretic peptide levels in hyperthyroidism are mainly driven by increased metabolism due to excess thyroid hormones. Therefore, serum levels of N-terminal-pro-B-type natriuretic peptide were studied during reduced cardiac work load by means of pharmacologically induced heart rate reduction in untreated hyperthyroidism. We designed a noncontrolled interventional study. Eighteen women with newly diagnosed hyperthyroidism were evaluated (including an echocardiography) before and after pharmacological heart rate reduction with 360 mg verapamil daily for 6 days. Before treatment, N-terminal-pro-B-type natriuretic peptide was independently associated with thyroid function (free triiodothyronine-index, r=0.64, p=0.001) and the hemoglobin concentration (r=-0.36, p=0.031). The verapamil treatment induced a decrease in parameters reflecting cardiac function; resting heart rate [from mean 97 to 80 beats per min (17.5%), p<0.001] and mean arterial pressure (8.5%, p=0.001). Median N-terminal-pro-B-type natriuretic peptide increased insignificantly from 224 to 240 pg/ml (p=0.31). Thyrotrotrophin levels were totally suppressed (<0.001 mU/l), free thyroxine-index decreased from median 319 to 315 arbitrary units (p=0.039) and free triiodothyronine-index increased from 8.6 to 9.9 arbitrary units (p=0.010). No changes in echocardiographic parameters were observed. A decrease in resting heart rate in untreated hyperthyroidism due to verapamil treatment did not result in decreasing N-terminal-pro-B-type natriuretic peptide levels. Thus elevated N-terminal-pro-B-type natriuretic peptide in hyperthyroidism seems mainly a result of high metabolism due to excess thyroid hormones rather than increased cardiac work load.

NT-pro-BNP during hypoglycemia and hypoxemia in normal subjects: impact of renin-angiotensin system activity.

Brain-derived natriuretic peptide (BNP) is a cardioprotective peptide released, together with the inactive NH(2)-terminal part of its prohormone (NT-pro-BNP), in response to different kinds of myocardial stress. Hypoglycemia and hypoxemia are conditions that threaten cellular function and hence potentially stimulate BNP release. BNP interacts with the renin-angiotensin system (RAS). The aim of this study was, therefore, to explore if basal RAS activity has an impact on NT-pro-BNP concentrations during myocardial stress induced by hypoglycemia and hypoxemia. From a cohort of 303 healthy young men, 10 subjects with high-RAS activity and 10 subjects with low-RAS activity (age 26 +/- 1 yr; mean +/- SE) were studied in a single-blinded, randomized, counterbalanced, crossover study on three occasions separated by at least 3 wk: 1) hypoglycemia (mean nadir plasma glucose 2.7 +/- 0.5 mmol/l), 2) hypoxemia (mean nadir Po(2) 5.8 +/- 0.5 kPa), and 3) normoglycemic normoxia (control). NT-pro-BNP was measured at baseline, during the stimuli, and in the recovery phase. Hypoxemia was associated with a 9% increase in NT-pro-BNP from 2.2 +/- 1.5 pmol/l at baseline to 2.4 +/- 1.5 pmol/l during hypoxemia (P < 0.001). Hypoglycemia did not affect the NT-pro-BNP level. RAS activity had no impact on NT-pro-BNP levels during hypoglycemia and hypoxemia. Hypoxemia, but not hypoglycemia, stimulates NT-pro-BNP. This indicates that cardiac defense mechanisms against hypoglycemia, if any, are probably different from those against hypoxemia. Basal RAS activity had no impact on NT-pro-BNP levels.

Insulin therapy improves insulin-stimulated endothelial function in patients with type 2 diabetes and ischemic heart disease.

Blunted insulin-stimulated endothelial function may be a mechanism for the development of atherothrombotic disease in type 2 diabetes, but it is unknown whether hypoglycemic drug therapy can modulate this abnormality. We studied patients with type 2 diabetes and stable ischemic heart disease (n = 28) and lean, healthy control subjects (n = 31). Forearm blood flow was measured by venous occlusion plethysmography during dose-response studies of acetylcholine (ACh) and sodium nitroprusside (SNP) infused into the brachial artery. In the patients and 10 healthy control subjects, ACh was repeated after intrabrachial infusion of insulin. Patients were restudied after 2 months of insulin therapy with four daily subcutaneous injections (treatment group, n = 19) or without hypoglycemic drug therapy (time control group, n = 9). Insulin infusion raised venous serum insulin in the forearm to high physiological levels (133 +/- 14.6 mU/l in patients) with a minor increase in systemic venous serum insulin. This increased the ACh response by 149 +/- 47, 110 +/- 33, 100 +/- 45, and 106 +/- 44% during the four ACh doses in healthy control subjects (P < 0.0001) but had no effect in patients (P = 0.3). After 2 months, HbA(1c) in the treatment group had decreased from 10.0 +/- 0.4 to 7.5 +/- 0.2%. Although neither the ACh response (P = 0.09) nor the SNP response (P = 0.4) had changed significantly, insulin stimulation had a significant effect, as the ACh response increased by 58 +/- 25, 84 +/- 66, 120 +/- 93, and 69 +/- 36% (P = 0.0002). In the time control group, insulin stimulation remained without effect after 8 weeks (P = 0.7). In conclusion, insulin therapy partly restores insulin-stimulated endothelial function in patients with type 2 diabetes and ischemic heart disease.

Measurements of body composition by dual-energy X-ray absorptiometry improve prediction of energy expenditure.

The prediction of energy expenditure by dual-energy X-ray absorptiometry (DXA) and bioimpedance analysis (BIA) was assessed in 35 healthy individuals of both sexes, with a mean body mass index (BMI) of 23.8 kg/m2 (range 18-33.8), and mean age of 30 years (22-40). Energy expenditure (EE) was measured under standard conditions in a respiration chamber, the total and regional body composition by DXA, and total body composition by BIA. When body composition was measured by BIA, 88.5% of the variation in 24-h EE was explained by lean body mass (LBM); this figure was increased by DXA, where total lean tissue mass (LTM) and total fat tissue mass (FTM) could account for 91.5% of the variation. Also, the prediction of resting energy expenditure (REE) was improved by DXA, from 88.1% to 89.8% (LBM vs. LTM, FTM). Measurements of regional body composition showed that trunk LTM was significantly superior as a predictor, especially of REE and sleeping EE (EE sleep), compared to the peripheral LTM; thus, the predictions of REE were 83% vs. 87% (peripheral vs. trunk), respectively; and the predictions of EE sleep were 83% vs. 89% (peripheral vs. trunk), respectively. Therefore, body composition measurements by DXA improved the prediction of EE. Trunk LTM was a superior predictor, especially of REE and EE sleep, compared to peripheral LTM. In conclusion, the present results suggest that measuring total and regional body composition by DXA can somewhat improve the prediction of EE.

Comparison of resting energy expenditure measurements by ventilated canopy and by respiration chamber.

The study compared measurements of resting energy expenditure (REE) by two methods, namely the commercially available ventilated canopy (Medgraphics CCM system) and the respiration chamber. Thirty-five healthy subjects of both sexes with a wide weight range (BMI 18-33.8 kg m-2) were measured on both systems. The linear regression equation was REEcanopy = 0.66 x REEresp.cham. + 61.1 (kJ h-1), and the corresponding SEE% was 8.6%. The correlation was high (r = 0.89). However, the mean REE measured using the ventilated canopy was 41 kJ h-1 (13%) lower than that using the respiration chamber (P < 0.01). The Medgraphics CCM canopy system seems valid for measurements of REE. However, the REE results measured by the canopy were systematically lower than when measured by the respiration chamber, but can be converted by the equation given with an accuracy error of 9%.

Body composition analysis by dual energy X-ray absorptiometry in female diabetics differ between manufacturers.

OBJECTIVE: Comparison of body composition results by two dual energy X-ray absorptiometry (DXA) instruments, namely QDR-2000 from Hologic Inc and from Lunar in subpopulations of lean and obese subjects. DESIGN: Cross-sectional study with 85 female diabetics (BMI 18-43 kg/m2) measured with both DXA instruments. RESULTS: The regression lines for fat tissue mass (FTM), FAT% and total body bone mineral content (TBMC), but not lean tissue mass (LTM), were different from the line of identity (P < 0.01). However, the relationships were high (r2 > 0.95), and the corresponding SEE%'s were low (0.8-4.8%), and were independent of BMI. FTM and FAT% measured by the QDR-2000 were 10% higher, and LTM and TBMC 6% lower, than by DPX (P < 0.001). CONCLUSIONS: There were lack of agreements between total body composition results by DPX Lunar, and QDR-2000 Hologic Inc. Individual results on the two systems cannot be directly compared. Standardization of body composition measurements by DXA is strongly needed.