Inverse association between liver fat content and hepatic glucose uptake in patients with type 2 diabetes mellitus

The objective of this research was to study (1) the mutual relationship between liver fat content (LFC) and hepatic glucose uptake (HGU) in patients with type 2 diabetes mellitus and (2) the relationship between changes in LFC and HGU uptake induced by rosiglitazone in these patients. Liver fat was measured with proton magnetic resonance spectroscopy and insulin-stimulated HGU with [¹⁸F]-labeled 2-fluoro-2-deoxyglucose positron emission tomography in 54 patients with type 2 diabetes mellitus and 8 healthy subjects. Measurements were repeated in diabetic patients after a 16-week intervention period with rosiglitazone (n = 27) or placebo (n = 27). Patients with diabetes had lower HGU (24.5 ± 14.2 vs 35.6 ± 9.7 μmol/[kg min], P < .01) and higher LFC (10.9% ± 9.2% vs 2.5% ± 1.4%, P < .001) compared with healthy subjects. Liver fat was inversely associated with HGU (r = −0.31, P < .05), but more strongly with whole-body insulin sensitivity and adiponectin levels. Rosiglitazone treatment reduced liver fat by 24.8% (P = .01 vs placebo) and increased HGU by 29.2% (P = .013 vs placebo). This decrease in LFC was best explained by the increment in suppression of nonesterified fatty acid levels during hyperinsulinemia (P < .001) and improved glycemic control (P = .034), but not by changes in HGU. A significant inverse relationship between LFC and HGU was observed, but changes were not related. This suggests that the beneficial effects of rosiglitazone on liver metabolism are indirect and can be partly explained by increased suppression of nonesterified fatty acid levels, leading to reduced liver fat.     

Cover Image,Volume 20, Issue 5

The cover image, by Elizabeth G. Mietlicki‐Baase et al., is based on the Original Article A vitamin B12 conjugate of exendin‐4 improves glucose tolerance without associated nausea or hypophagia in rodents, DOI: 10.1111/dom.13222 .

     

Comparison of MRI and positron emission tomography for measuring myocardial perfusion reserve in healthy humans.

Myocardial perfusion reserve (MPR, defined as the ratio of the maximum myocardial blood flow (MBF) to the baseline) is an indicator of coronary artery disease and myocardial microvascular abnormalities. First-pass contrast-enhanced magnetic resonance imaging (CE-MRI) using gadolinium (Gd)-DTPA as a contrast agent (CA) has been used to assess MPR. Tracer kinetic models based on compartmental analysis of the CA uptake have been developed to provide quantitative measures of MBF by MRI. To study the accuracy of Gd-DTPA first-pass MRI and kinetic modeling for quantitative analysis of myocardial perfusion and MPR during dipyridamole infusion, we conducted a comparison with positron emission tomography (PET) in 18 healthy males (age = 40 +/- 14 years). Five planes were acquired at every second heartbeat with a 1.5T scanner using a saturation recovery turboFLASH sequence. A perfusion-related parameter, the unidirectional influx constant (Ki), was computed in three coronary artery territories. There was a significant correlation for both dipyridamole-induced flow (0.70, P = 0.001) and MPR (0.48, P = 0.04) between MRI and PET. However, we noticed that MRI provided lower MPR values compared to PET (2.5 +/- 1.0 vs. 4.3 +/- 1.8). We conclude that MRI supplemented with tracer kinetic modeling can be used to quantify myocardial perfusion.     

Measurement of brown adipose tissue mass using a novel dual-echo magnetic resonance imaging approach: A validation study

Objective

The aim of this study was to evaluate and validate magnetic resonance imaging (MRI) for the visualization and quantification of brown adipose tissue (BAT) in vivo in a rat model. We hypothesized that, based on differences in tissue water and lipid content, MRI could reliably differentiate between BAT and white adipose tissue (WAT) and could therefore be a possible alternative for ¹⁸ F-Fluorodeoxyglucose Positron Emission Tomography (¹⁸FDG-PET), the current gold standard for non-invasive BAT quantification.

Materials/Methods

Eleven rats were studied using both ¹⁸FDG-PET/CT and MRI (1.5 T). A dual echo (in-and-out-of-phase) sequence was used, both with and without spectral presaturation inversion recovery (SPIR) fat suppression (DUAL-SPIR) to visualize BAT, after which all BAT was surgically excised. The BAT volume measurements obtained via ¹⁸FDG-PET/CT and DUAL-SPIR MR were quantitatively compared with the histological findings. All study protocols were reviewed and approved by the local ethics committee.

Results

The BAT mass measurements that were obtained using DUAL-SPIR MR subtraction images correlated better with the histological findings (P = 0.017, R = 0.89) than did the measurements obtained using ¹⁸FDG-PET/CT (P = 0.78, R = 0.15), regardless of the BAT metabolic activation state. Additionally, the basic feasibility of the DUAL-SPIR method was demonstrated in three human pilot subjects.

Conclusions

This study demonstrates the potential for MRI to reliably detect and quantify BAT in vivo. MRI can provide information beyond that provided by ¹⁸FDG-PET imaging, and its ability to detect BAT is independent of its metabolic activation state. Additionally, MRI is a low-cost alternative that does not require radiation.     

Can patients’ narratives in nursing enhance the healing process?

Although there is a growing acknowledgement of the potential of a more nuanced healthcare paradigm and practice, the discourses of health promotion—and with that nursing and other healthcare professionals’ practice—still tend to focus on the medical diagnosis, disease and the rationale of biomedicine. There is a need for shifting to a human practice that draws on a broader perspective related to illness. This requires a transformation of practices which can be constructed within a narrative understanding. A narrative approach appreciates the importance of emotion and intersubjective relation in the telling and listening that occur in the clinical encounter. The essence of nursing lies in the creative imagination, the sensitive spirit and the intelligent understanding of the individuals’ possibilities of becoming empowered in his or her own life. This entails that the focus of the use of patients’ narratives is, ultimately, not the story itself, but the nurses’ and other healthcare professionals’ ability to support the patients in finding useful meaning in their stories. Herein, it is of particular importance to let the patients narrate about what is sparkling moments or events in the lived life. Stories with such focus can open up for patients’ hopes and dreams, which gives inspiration for finding meaningful ways to cope in life empowering personal recovery. It is, therefore, crucial to transform clinical settings into places that acknowledge the need for imagination and creativity, aiming at creating the opportunity for sensibility and vision essential to encouraging a narrative approach and thereby the ability to reflect upon and promote a healing process.