In vivo mapping of postprandial hepatic glucose metabolism using dynamic magnetic resonance spectroscopy combined with stable isotope flux analysis in Roux-en-Y gastric bypass adults and non-operated controls: A case-control study.

AIMS: Roux-en-Y gastric bypass (RYGB) surgery alters postprandial glucose profiles, causing post-bariatric hypoglycaemia (PBH) in some individuals. Due to the liver's central role in glucose homeostasis, hepatic glucose handling might differ in RYGB-operated patients with PBH compared to non-operated healthy controls (HC). MATERIALS AND METHODS: We enrolled RYGB-operated adults with PBH and HCs (n = 10 each). Participants ingested 60 g of [6,6'-2H2]-glucose (d-glucose) after an overnight fast. Deuterium metabolic imaging (DMI) with interleaved 13C magnetic resonance spectroscopy was performed before and until 150 min post-d-glucose intake, with frequent blood sampling to quantify glucose enrichment and gluco-regulatory hormones until 180 min. Glucose fluxes were assessed by mathematical modelling. Outcome trajectories were described using generalized additive models. RESULTS: In RYGB subjects, the hepatic d-glucose signal increased early, followed by a decrease, whereas HCs exhibited a gradual increase and consecutive stabilization. Postprandial hepatic glycogen accumulation and the suppression of endogenous glucose production were lower in RYGB patients than in HCs, despite higher insulin exposure, indicating lower hepatic insulin sensitivity. The systemic rate of ingested d-glucose was faster in RYGB, leading to a higher, earlier plasma glucose peak and increased insulin secretion. Postprandial glucose disposal increased in RYGB patients, without between-group differences in peripheral insulin sensitivity. CONCLUSIONS: Exploiting DMI with stable isotope flux analysis, we observed distinct postprandial hepatic glucose trajectories and parameters of glucose-insulin homeostasis in RYGB patients with PBH versus HCs. Despite altered postprandial glucose kinetics and higher insulin exposure, there was no evidence of impaired hepatic glucose uptake or output predisposing to PBH in RYGB patients.

Effects of sacubitril/valsartan on the functional capacity of real-world patients in Italy: the REAL.IT study on heart failure with reduced ejection fraction.

Background: Heart failure (HF) significantly affects the morbidity, mortality, and quality of life of patients. New therapeutic strategies aim to improve the functional capacity and quality of life of patients while controlling HF-related risks. Real-world data on both the functional and cardiopulmonary exercise capacities of patients with HF with reduced ejection fraction upon sacubitril/valsartan use are lacking. Methods: A multicenter, retrospective, cohort study, called REAL.IT, was performed based on the data collected from the electronic medical records of nine specialized HF centers in Italy. Cardiopulmonary exercise testing was performed at baseline and after 12 months of sacubitril/valsartan therapy, monitoring carbon dioxide production (VCO2) and oxygen consumption (VO2). Results: The functional capacities of 170 patients were evaluated. The most common comorbidities were hypertension and diabetes (i.e., 53.5 and 32.4%, respectively). At follow-up, both the VO2 peak (from 15.1 ± 3.7 ml/kg/min at baseline to 17.6 ± 4.7 ml/kg/min at follow-up, p < 0.0001) and the predicted % VO2 peak (from 55.5 ± 14.1 to 65.5 ± 16.9, p < 0.0001) significantly increased from baseline. The VO2 at the anaerobic threshold (AT-VO2) increased from 11.5 ± 2.6 to 12.5 ± 3.3 ml/kg/min (p = 0.021), and the rate ratio between the oxygen uptake and the change in work (ΔVO2/Δwork slope) improved from 9.1 ± 1.5 to 9.9 ± 1.6 ml/min/W (p < 0.0001). Conclusions: Sacubitril/valsartan improves the cardiopulmonary capacity of patients with HFrEF in daily clinical practice in Italy.

Interleaved trinuclear MRS for single-session investigation of carbohydrate and lipid metabolism in human liver at 7T.

The liver plays a central role in metabolic homeostasis, as exemplified by a variety of clinical disorders with hepatic and systemic metabolic disarrays. Of particular interest are the complex interactions between lipid and carbohydrate metabolism in highly prevalent conditions such as obesity, diabetes, and fatty liver disease. Limited accessibility and the need for invasive procedures challenge direct investigations in humans. Hence, noninvasive dynamic evaluations of glycolytic flux and steady-state assessments of lipid levels and composition are crucial for basic understanding and may open new avenues toward novel therapeutic targets. Here, three different MR spectroscopy (MRS) techniques that have been combined in a single interleaved examination in a 7T MR scanner are evaluated. 1H-MRS and 13C-MRS probe endogenous metabolites, while deuterium metabolic imaging (DMI) relies on administration of deuterated tracers, currently 2H-labelled glucose, to map the spatial and temporal evolution of their metabolic fate. All three techniques have been optimized for a robust single-session clinical investigation and applied in a preliminary study of healthy subjects. The use of a triple-channel 1H/2H/13C RF coil enables interleaved examinations with no need for repositioning. Short-echo-time STEAM spectroscopy provides well resolved spectra to quantify lipid content and composition. The relative benefits of using water saturation versus metabolite cycling and types of respiratory synchronization were evaluated. 2H-MR spectroscopic imaging allowed for registration of time- and space-resolved glucose levels following oral ingestion of 2H-glucose, while natural abundance 13C-MRS of glycogen provides a dynamic measure of hepatic glucose storage. For DMI and 13C-MRS, the measurement precision of the method was estimated to be about 0.2 and about 16 mM, respectively, for 5 min scanning periods. Excellent results were shown for the determination of dynamic uptake of glucose with DMI and lipid profiles with 1H-MRS, while the determination of changes in glycogen levels by 13C-MRS is also feasible but somewhat more limited by signal-to-noise ratio.

Getting the phase consistent: The importance of phase description in balanced steady-state free precession MRI of multi-compartment systems.

PURPOSE: Determine the correct mathematical phase description for balanced steady-state free precession (bSSFP) signals in multi-compartment systems. THEORY AND METHODS: Based on published bSSFP signal models, different phase descriptions can be formulated: one predicting the presence and the other predicting the absence of destructive interference effects in multi-compartment systems. Numerical simulations of bSSFP signals of water and acetone were performed to evaluate the predictions of these different phase descriptions. For experimental validation, bSSFP profiles were measured at 3T using phase-cycled bSSFP acquisitions performed in a phantom containing mixtures of water and acetone, which replicates a system with two signal components. Localized single voxel MRS was performed at 7T to determine the relative chemical shift of the acetone-water mixtures. RESULTS: Based on the choice of phase description, the simulated bSSFP profiles of water-acetone mixtures varied significantly, either displaying or lacking destructive interference effects, as predicted theoretically. In phantom experiments, destructive interference was consistently observed in the measured bSSFP profiles of water-acetone mixtures, supporting the theoretical description that predicts such interference effects. The connection between the choice of phase description and predicted observation enables unambiguous experimental identification of the correct phase description for multi-compartment bSSFP profiles, which is consistent with the Bloch equations. CONCLUSION: The study emphasizes that consistent phase descriptions are crucial for accurately describing multi-compartment bSSFP signals, as incorrect phase descriptions result in erroneous predictions.

Pharmacoutilization and adherence to sacubitril/valsartan in real world: the REAL.IT study in HFrEF.

AIMS: The current European Society of Cardiology (ESC) guidelines provide clear indications for the treatment of acute and chronic heart failure (HF). Nevertheless, there is a constant need for real-world evidence regarding the effectiveness, adherence, and persistence of drug therapy. We investigated the use of sacubitril/valsartan for the treatment of HF with reduced ejection fraction in real-world clinical practice in Italy. METHODS AND RESULTS: An observational, retrospective, non-interventional cohort study based on electronic medical records from nine specialized hospital HF centres in Italy was carried out on patients with prescription of sacubitril/valsartan. Overall, 948 patients had a prescription of sacubitril/valsartan, with 924 characterized over 6 months and followed up for 12 months. Pharmacoutilization data at 1 year of follow-up were available for 225 patients {mean age 69.7 years [standard deviation (SD) = 10.8], 81.8% male}. Of those, 398 (45.2%) reached the target dose of sacubitril/valsartan of 97/103 mg in a mean time of 6.9 (SD = 6.2) weeks. Blood pressure and hypotension in 61 patients (65%) and worsening of chronic kidney disease in 10 patients (10.6%) were the main reasons for not reaching the target dose. Approximatively 50% of patients had a change in sacubitril/valsartan dose during follow-up, and 158 (70.2%) were persistent with the treatment during the last 3 months of follow-up. A sensitivity analysis (persistence during the last 4 months of follow-up) showed persistence for 162 patients (72.0%). Adherence data, available for 387 patients, showed full adherence for 205 (53%). Discontinuation (102/717 patients, 14.2%) was mainly due to hypotension and occurred after a mean time of 34.3 (SD = 28.7) weeks. During follow-up, out of 606 patients with available data, 434 patients (71.6%) had an HF add-on drug or drugs concomitant with sacubitril/valsartan. HF-related hospitalization during follow-up was numerically higher in non-persistent (16/67 patients, 23.9%) vs. patients persistent to sacubitril/valsartan (30/158, 19%) (P = 0.405). CONCLUSIONS: Real-world data on the use of sacubitril/valsartan in clinical practice in Italy show a rapid titration to the target dose, high therapeutic adherence enabling a good level of therapeutic management in line with ESC guidelines for patients with reduced ejection fraction.

Sacubitril/Valsartan in Heart Failure with Reduced Ejection Fraction: Real-World Experience from Italy (the REAL.IT Study).

Sacubitril/valsartan reduces heart failure (HF)-related hospitalizations and cardiovascular mortality in PARADIGM-HF and has become a foundational treatment for HF with reduced ejection fraction (HFrEF). However, data of its routine real-world use are limited, and evidence from Italian settings is lacking. The REAL.IT study aimed to characterize the demographics, pharmacotherapy, clinical characteristics and outcomes of sacubitril/valsartan-treated Italian patients with HFrEF. Electronic medical records of patients initiating sacubitril/valsartan from October 2016 to June 2019 at nine specialized hospital outpatient HF centers across Italy were reviewed. Overall, 924 adults (mean age 64.5 years, 84.6% male) were included. At baseline, 38.7% had an ischemic HF etiology, 45.9% hypertension, 23.2% atrial fibrillation, 25.4% diabetes mellitus, 26.1% an implantable cardioverter-defibrillator and 31.9% coronary artery bypass grafting. There were no clear patterns of patient selection over time. During follow-up, NYHA class improved in 37.5% of patients after a mean of 5.3 ± 3.8 months; 36.1% and 16.7% of patients were in NYHA class III during characterization and after one year of follow-up, respectively. Left ventricular ejection fraction (LVEF) improved ≥5% in 56.3% of patients at one year; 39.7% had ≥30% reduction of N-terminal pro-B-type natriuretic peptide; 2.2% had hyperkalemia during characterization and 2.6% during follow-up; and 3.8% had hypotension during characterization and 12% during follow-up. A total of 50 (5.8%) of patients had device implantation (ICD/CRT) during follow-up. HF-related hospitalization was recorded in 19.6% of patients during follow-up; 3.8% of patients died, approximately 1.3% from cardiovascular causes. Our real-world data confirm the favorable effectiveness and tolerability of sacubitril/valsartan observed in pivotal randomized controlled trials.

Influence of threshold value in the use of statistical methods for groundwater vulnerability assessment.

Statistical techniques can be used in groundwater pollution problems to determine the relationships among observed contamination (impacted wells representing an occurrence of what has to be predicted), environmental factors that may influence it and the potential contamination sources. Determination of a threshold concentration to discriminate between impacted or non impacted wells represents a key issue in the application of these techniques. In this work the effects on groundwater vulnerability assessment by statistical methods due to the use of different threshold values have been evaluated. The study area (Province of Milan, northern Italy) is about 2000 km(2) and groundwater nitrate concentration is constantly monitored by a net of about 300 wells. Along with different predictor factors three different threshold values of nitrate concentration have been considered to perform the vulnerability assessment of the shallow unconfined aquifer. The likelihood ratio model has been chosen to analyze the spatial distribution of the vulnerable areas. The reliability of the three final vulnerability maps has been tested showing that all maps identify a general positive trend relating mean nitrate concentration in the wells and vulnerability classes the same wells belong to. Then using the kappa coefficient the influence of the different threshold values has been evaluated comparing the spatial distribution of the resulting vulnerability classes in each map. The use of different threshold does not determine different vulnerability assessment if results are analyzed on a broad scale, even if the smaller threshold value gives the poorest performance in terms of reliability. On the contrary, the spatial distribution of a detailed vulnerability assessment is strongly influenced by the selected threshold used to identify the occurrences, suggesting that there is a strong relationship among the number of identified occurrences, the scale of the maps representing the predictor factors and the model efficiency in discriminating different vulnerable areas.

Spatial and statistical assessment of factors influencing nitrate contamination in groundwater.

The weights of evidence (WofE) modeling technique has been used to analyze both natural and anthropogenic factors influencing the occurrence of high nitrate concentrations in groundwater resources located in the central part of the Po Plain (Northern Italy). The proposed methodology applied in the Lodi District combines measurements of nitrate concentrations, carried out by means of a monitoring net of 69 wells, with spatial data representing both categorical and numerical variables. These variables describe either potential sources of nitrate and the relative ease with which it may migrate towards groundwater. They include population density, nitrogen fertilizer loading, groundwater recharge, soil protective capacity, vadose zone permeability, groundwater depth, and saturated zone permeability. Once conditional dependence problems among factors have been solved and validation tests performed, the statistical approach has highlighted negative and positive correlations between geoenvironmental factors and nitrate concentration in groundwater. These results have been achieved analysing the calculated statistical parameters (weights, contrasts, normalized contrasts) of each class by which each factor has been previously subdivided. This has permitted to outline: the overall influence each factor has on the presence/absence of nitrate; the range of their values mostly influencing this presence/absence; the most and least critical combination of factor classes existing in each specific zone; areas where the influence of impacting factor classes is reduced by the presence of not impacting factor classes. This last aspect could represent an important support for a correct land use management to preserve groundwater quality.