Longitudinal Assessment of Critical Thinking Skills Across a Dental Curriculum.

Critical thinking and problem-solving are two of the most frequently desired goals for dental student learning, but greater understanding is needed of how students' critical thinking skills develop from the beginning to the end of the curriculum. The aim of this study was to use students' performance on critical thinking assessments at five time points from the first to the fourth years to longitudinally assess their critical thinking development across the curriculum. In 2014-16, the performance of students in two successive graduating classes at one U.S. dental school was collected from five assignments designed to, among other things, assess critical thinking. Those assignments ranged from a case study in the Cariology I course in fall of the first year to an OSCE completed before graduation. Students were divided into four quartiles from lowest- to highest-achieving based on the first (baseline) assessment, and those quartiles were tracked to determine each student's progress over the four years. The results showed that, for both cohorts, students who ranked in the top quartile remained in the top of the class for all subsequent assessments. Also in both cohorts, the students who had the lowest scores on the initial assessment of critical thinking skills showed statistically significant improvements over time, increasing their scores by 9.4% (cohort 1, p<0.001) and 4.6% (cohort 2, p=0.003) in each consecutive assessment. These results suggest that implementing critical thinking assessments early in the curriculum can assist in predicting students' future performance on critical thinking assessments. Furthermore, a dental curriculum intentionally designed to promote critical thinking capacities can help students improve these skills over time, whatever their level at the beginning.

Lipid mixtures containing a very high proportion of saturated fatty acids only modestly impair insulin signaling in cultured muscle cells.

In vitro examinations of the effect of saturated fatty acids on skeletal muscle insulin action often use only one or two different fatty acid species, which does not resemble the human plasma fatty acid profile. We compared graded concentrations (0.1-0.8 mM) of 3 different lipid mixtures: 1) a physiologic fatty acid mixture (NORM; 40% saturated fatty acids), 2) a physiologic mixture high in saturated fatty acids (HSFA; 60% saturated fatty acids), and 3) 100% palmitate (PALM) on insulin signaling and fatty acid partitioning into triacylglycerol (TAG) and diacylglycerol (DAG) in cultured muscle cells. As expected, PALM readily impaired insulin-stimulated pAktThr308/Akt and markedly increased intracellular DAG content. In contrast, the fatty acid mixtures only modestly impaired insulin-stimulated pAktThr308M/Akt, and we found no differences between NORM and HSFA. Importantly, NORM and HSFA did not increase DAG content, but instead dose-dependently increased TAG accumulation. Therefore, the robust impairment in insulin signaling found with palmitate exposure was attenuated with physiologic mixtures of fatty acids, even with a very high proportion of saturated fatty acids. This may be explained in part by selective partitioning of fatty acids into neutral lipid (i.e., TAG) when muscle cells were exposed to physiologic lipid mixtures.

A single session of low-intensity exercise is sufficient to enhance insulin sensitivity into the next day in obese adults.

OBJECTIVE: The purpose of this study was to determine the effect of a relatively modest session of exercise on insulin sensitivity and fatty acid uptake the next day in obese adults. RESEARCH DESIGN AND METHODS: Eleven sedentary obese adults (male/female: 3/8; BMI 37 ± 1 kg/m(2); peak oxygen uptake [VO2peak] 20 ± 1 mL/kg/min) completed three experimental trials. On two of these occasions, subjects exercised to expend 350 kcal in the afternoon. These two exercise trials were identical except for the exercise intensity (50% VO2peak [EX50] and 65% VO2peak [EX65]) and the duration of exercise necessary to expend 350 kcal (EX50 = ≈ 70 min; EX65 = ≈ 55 min). Subjects also completed a control trial (CON), without exercise. The next morning, we measured insulin sensitivity (hyperinsulinemic-euglycemic clamp) and whole-body fatty acid uptake (palmitate rate of disappearance from plasma [Rd]). RESULTS: Exercise increased insulin sensitivity the next day, but whereas the 35% improvement after EX50 compared with CON was statistically significant (P = 0.01), the 20% improvement after EX65 was not (P = 0.17). Despite nearly identical values between CON and EX65 (P = 0.88), systemic fatty acid uptake was lower after EX50 compared with EX65 (P = 0.02), but not quite significant compared with CON (P = 0.07). Importantly, the change in fatty acid uptake after exercise compared with CON was negatively correlated with the change in insulin sensitivity for all trials (r = -0.60, P = 0.003). CONCLUSIONS: A relatively modest single session of exercise in obese adults improved insulin sensitivity the next day, and a reduction in systemic fatty acid uptake in the several hours after exercise may be important for this effect.

High fatty acid availability after exercise alters the regulation of muscle lipid metabolism.

We previously reported that a single exercise session protects against fatty acid (FA)-induced insulin resistance, perhaps in part through augmented intramyocellular triacylglycerol (IMTG) synthesis. The aim of this study was to examine the effect of elevated FA availability after exercise on factors regulating IMTG metabolism. After exercise (90 minutes, 65% peak oxygen uptake), 7 healthy women (body mass index, 23 ± 1 kg/m(2)) were infused overnight (16 hours) with either a lipid and heparin solution (LIPID, 0.11 g fat per kilogram per hour) or saline (SALINE). We measured resting FA oxidation (indirect calorimetry) and obtained a skeletal muscle biopsy sample the next morning. The 4-fold increase in overnight plasma FA concentration during LIPID increased IMTG by approximately 30% during LIPID vs SALINE. This was accompanied by an approximately 25% greater membrane-associated abundance of the FA transporter FAT/CD36 (P < .01) and an approximately 8% increase in the activity of the IMTG synthesis enzyme glycerol-3-phosphate acyltransferase (GPAT, P < .01). In contrast, resting FA oxidation was not affected. We also found no difference in the protein abundance of GPAT1 and diacylglycerol acyltransferase-1, diacylglycerol acyltransferase activity, or the abundance of the lipid droplet coat proteins (perilipins 2, 3, 4, and 5) between treatments. Our findings suggest that augmented capacity for FA flux into muscle (ie, via membrane-associated FAT/CD36), perhaps together with a slight yet significant increase in activity of a key IMTG synthesis enzyme (GPAT), may enhance IMTG storage when FA availability is high after exercise. The importance of the absence of a change in perilipin protein abundance despite increased muscle lipid storage remains to be determined.