[Insulin resistance: the role of intramuscular triglyceride and the importance of physical activity]. / Insulineresistentie: de rol van intramusculair triacylglycerol en het nut van fysieke inspanning.

In the Netherlands, the prevalence of diabetes is expected to rise from 480,000 to more than 650,000 patients by the year 2020. Numerous studies have reported a strong correlation between elevated plasma-free fatty-acid levels, the accumulation of intramuscular triglyceride (IMTG) and the development of insulin resistance. Traditionally, the Randle cycle was used to explain the mechanism behind fatty acid-induced insulin resistance in skeletal muscle. An alternative explanation is that the increased supply of free fatty acids leads to the accumulation of IMTG and fatty-acid metabolites, which can induce defects in the insulin signalling cascade, causing insulin resistance in skeletal muscle. However, this proposed relationship between elevated IMTG concentrations and skeletal-muscle insulin resistance does not always apply, as trained athletes have been shown to be markedly insulin-sensitive, despite having high levels of stored IMTG. This metabolic paradox is explained by the fact that it is not the size of the IMTG pool but rather the balance between fatty-acid availability, uptake and oxidation, i.e. the low turnover of the IMTG pool, that is instrumental in the development of skeletal-muscle insulin resistance. Physical exercise forms an effective strategy to improve the balance between skeletal-muscle fatty-acid uptake and oxidation and, as such, can prevent the development of skeletal-muscle insulin resistance.

Contrast echocardiography clarifies uninterpretable wall motion in intensive care unit patients.

OBJECTIVES: The study examined the value of contrast echocardiography in the assessment of left ventricular (LV) wall motion in intensive care unit (ICU) patients. BACKGROUND: Echocardiograms done in the ICU are often suboptimal. The most common indication is the evaluation of LV wall motion and ejection fraction (EF). METHODS: Transthoracic echocardiograms were done in 70 unselected ICU patients. Wall motion was evaluated on standard echocardiography (SE), harmonic echocardiography (HE), and after intravenous (IV) contrast echocardiography (CE) using a score for each of 16 segments. A confidence score was also given for each segment with each technique (unable to judge; not sure; sure). The EF was estimated visually for each technique, and a confidence score was applied to the EF. RESULTS: Uninterpretable wall motion was present in 5.4 segments/patient on SE, 4.4 on HE (p = 0.2), and 1.1 on CE (p < 0.0001). An average of 7.8 segments were read with surety on SE, 9.2 on HE (p = 0.1), and 13.7 on CE (p < 0.0001). Ejection fraction was uninterpretable in 23% on SE, 13% on HE (p = 0.14), and 0% on CE (p = 0.002 vs. HE; p < 0.0001 vs. SE). The EF was read with surety in 56% of patients on SE, 62% on HE (p = 0.47), and 91% on CE (p < 0.0001). Thus, wall motion was seen with more confidence on CE. More importantly, the actual readings of segmental wall motion and EF significantly differed using CE. CONCLUSIONS: CE should be used in all ICU patients with suboptimal transthoracic echocardiograms.