Characteristics of oleate binding to liver plasma membranes and its uptake by isolated hepatocytes

To clarify mechanisms of hepatic free fatty acid uptake, [3H]oleate uptake by isolated rat hepatocytes was studied, using solutions of 150 microM bovine serum albumin at oleate:albumin molar ratios of 0.033-6.7:1. Oleate partitioning between liver plasma membranes and albumin was also studied, and used to ascertain the membrane binding function for oleate. The experimental uptake curve was complex, but could be resolved by computer fitting into a sum of two components, one a saturable and the second a linear function of the unbound oleate concentration. The saturable component comprises > 90% of total oleate uptake when the oleate:albumin molar ratio is < 2.5, but < 50% when this ratio is > 5. Membrane binding also consisted of a sum of a saturable and a linear component. By comparison of the computer-fitted uptake and binding functions, separate rate constants for the transfer into the cell of the saturably and non-saturably bound oleate were estimated to be 0.7 s-1 and 0.05 s-1, respectively. The former is compatible with a specific, protein-mediated process. It is 15-times greater than the corresponding rate constant for transfer of non-saturably bound oleate into the cell, which in turn is similar to reported rates of non-specific 'flip-flop' of fatty acids across lipid bilayers. The observed kinetics are not consistent with models in which uptake occurs principally from the albumin-bound pool of oleate, or solely from the oleate which has partitioned passively into the lipid bilayer of the plasma membrane.     

Assessment programs to enhance learning

Background: Assessment is an essential part of the educational system. Usually, assessment is used to measure students’ knowledge, but it can also be used to drive students’ learning and behaviors. Assessment programs should be constructed in a well-balanced way allowing not only measuring students’ knowledge but also changing students’ behavior.

Objectives: In this paper, we will discuss different strategies that can be used to change students’ behaviors which may improve their learning.

Main findings: Assessment as well as the learning material should be congruent with the objectives. Based on the literature, we summarize findings that would address key points to allow assessment for learning instead of learning.

Conclusions: When constructing an assessment program, choices have to be made that depend on aspects like logistics, financial, organizational, managerial, educational culture, and cooperation of individual and key faculty members. It is important to realize that whatever decisions you make, students will always adapt their behavior to the way you construct your assessment program.     

Ruxolitinib in Aicardi-Goutières syndrome

Metabolic Brain Disease - Aicardi-Goutières Syndrome (AGS) is a monogenic leukodystrophy with pediatric onset, clinically characterized by a variable degree of neurologic impairment. It...     

Hemodynamic effects of somatostatin in insulin-dependent diabetic subjects

Summary The aim of the present study was to evaluate possible hemodynamic effects of somatostatin in insulin-dependent diabetic subjects. For this purpose, 7 insulin-requiring juvenile-onset diabetics were submitted to a short-term infusion of cyclic somatostatin (250 μg/h, over 2 h) or saline in randomized order. Somatostatin infusion resulted in a progressive and significant decrease in heart rate, stroke volume, cardiac index and velocity circumferential fiber; on the other hand, left ventricular ejection time was augmented by somatostatin. None of these effects was seen in the saline control study. We conclude that somatostatin exerts a negative inotropic effect in insulin-dependent diabetes.     

Truncal fat determined by dual-energy X-ray absorptiometry is an independent predictor of coronary artery disease extension

BACKGROUND: Controversy prevails regarding the existence of a correlation between the severity of coronary artery disease (CAD) and the extent and distribution of obesity. PURPOSE: To assess the correlation between total fat, truncal fat (TF), and lean mass, obtained with dual-energy X-ray absorptiometry (DEXA) and standard anthropomorphic indices (body mass index, waist circumference, waist-to-hip ratio) and to verify whether DEXA indices can predict the extent and severity of CAD. MATERIALS AND METHODS: Fifty-eight patients (19 females) consecutively referred for coronary angiography underwent physical examination and DEXA assessment of body composition. RESULTS: Of the 58 patients enrolled, 22 were overweight and 13 were obese. Significant CAD was found in 39 (67%) patients. DEXA-derived total mass and fat mass enabled us to distinguish overweight from obese patients (P<0.005), whereas just TF mass correlated with the number of diseased vessels after adjusting for body mass index, sex, age, and smoking habit (odds ratio, 8.68; 95% confidence interval: 1.02-74.10). CONCLUSION: TF determined by DEXA is independently related with CAD extension.