H and ex vivo2 H magnetic resonance spectroscopy before and during hyperinsulinemiceuglycemic clamps with isotope dilution. Mice underwent identical clamp procedures and hepatic transcriptome analyses.RESULTS. PO administration decreased whole-body, hepatic, and adipose tissue insulin sensitivity by 25%, 15%, and 34%, respectively. Hepatic triglyceride and ATP content rose by 35% and 16%, respectively. Hepatic gluconeogenesis increased by 70%, and net glycogenolysis declined by 20%. Mouse transcriptomics revealed that PO differentially regulates predicted upstream regulators and pathways, including LPS, members of the TLR and PPAR families, NF-κB, and TNF-related weak inducer of apoptosis (TWEAK). CONCLUSION.Saturated fat ingestion rapidly increases hepatic lipid storage, energy metabolism, and insulin resistance. This is accompanied by regulation of hepatic gene expression and signaling that may contribute to development of NAFLD. PO results in increased circulating TG, glucagon, and incretins. After PO administration, TG in plasma rose by 59% (area under the time curve [AUC], P < 0.001) and by 156% in chylomicrons (AUC, P = 0.009) (Figure 2A). The AUC for plasma free fatty acids (FFA) ( Figure 2B) and insulin concentrations ( Figure 2C) was unchanged, while the AUC for plasma C-peptide was 28% higher after PO ingestion versus VCL (P < 0.005, Figure 2D). Of note, FFA were increased at 300, 420, and 480 minutes. Blood glucose levels were not different between PO-and VCL-treated groups ( Figure 2E). Plasma glucagon rose by 41% (AUC, P < 0.0001) only after PO ingestion ( Figure 2F). Also, glucagon-like peptide 1 (GLP-1) and gastric inhibitory polypeptide (GIP) levels were markedly increased and remained elevated after PO ingestion (both P < 0.005) (Supplemental Figure 2; supplemental material available online with this article; https://doi.org/10.1172/ JCI89444DS1). Circulating levels of TNF-α, IL-6, fetuin-A, chemerin, omentin, and cortisol were not different between PO and VCL groups (P > 0.5 for all) (Supplemental Table 1). REGISTRATION. The Journal of Clinical Investigation C L I N I C A L M E D I C I N EPO induces insulin resistance at whole-body, liver, and adipose tissue levels. Insulin sensitivity was measured using hyperinsulinemic-euglycemic clamp tests in healthy humans. Steady state was reached (Supplemental Figure 1), and pertinent parameters were analyzed during this time. PO ingestion reduced WBIS by 25% compared with VCL treatment (P = 0.0005, Figure 3A). Furthermore, after PO, volunteers also showed a decrease of 22% (P = 0.002) in the rate of glucose disappearance (Rd), mostly due to a 33% (P = 0.01) reduction in glucose oxidation (GOX), while the rate of nonoxidative glucose disposal remained unchanged

Aims/hypothesis This study aimed to perform a comprehensive analysis of interlobular, intralobular and parenchymal pancreatic fat in order to assess their respective effects on beta cell function. Methods Fifty-six participants (normal glucose tolerance [NGT] (n=28), impaired fasting glucose (IFG) and/or impaired glucose tolerance (IGT) (n=14) and patients with type 2 diabetes (n=14)) underwent a frequent-sampling OGTT and non-invasive magnetic resonance imaging (MRI; whole-body and pancreatic) and proton magnetic resonance spectroscopy ( 1 H-MRS; liver and pancreatic fat). Total pancreatic fat was assessed by a standard 2 cm H-MRS techniques revealed an inhomogeneous distribution of interlobular and intralobular adipose tissue, which increased with decreasing glucose tolerance. mDIXON-MRI measurements provided evidence against uniform steatosis, revealing regions of parenchymal tissue void of lipid accumulation in all participants. Total (r=0.385, p<0.01) and intralobular pancreas adipose tissue infiltration (r=0.310, p< 0.05) positively associated with age, but not with fasting or 2 h glucose levels, BMI or visceral fat content (all p>0.5). Furthermore, no associations were found between total and intralobular pancreatic adipose tissue infiltration and insulin secretion or beta cell function within NGT, IFG/IGT or patients with type 2 diabetes (all p>0.2). Conclusions/interpretation The pancreas does not appear to be another target organ for abnormal endocrine function because of ectopic parenchymal fat storage. No relationship was found between pancreatic adipose tissue infiltration and beta cell function, regardless of glucose tolerance status.

An efficient breathing system was designed for direct 17 O MRI to perform oxygen metabolism studies of the human brain. The breathing system consists of a demand oxygen delivery device for 17 O 2 supply and a custom-built rebreathing circuit with pneumatic switching valve. To efficiently deliver the 17 O gas to the alveoli of the lungs, the system applies short gas pulses upon an inspiration trigger via a nasal cannula. During and after 17 O 2 administration, the exhaled gas volumes are stored and filtered in the re-breathing section to make the most efficient use of the rare 17 O gas. In an inhalation experiment, 2.2 6 0.