Increased Energy Drink Use as a Predictor of Illicit Prescription Stimulant Use.

BACKGROUND: The purpose of this study was to examine energy drink usage patterns and to investigate the relationship between energy drink use and illicit use of prescription stimulants among college students. METHODS: A sample of 605 undergraduate and graduate students (mean age±SD: 21.96±4.216) from a large midwestern university voluntarily participated in the study. RESULTS: Of the participants, 48.9% (n=296) reported using energy drinks in the past 30 days, whereas 25.3% (n=153) reported using prescription stimulant drugs in the past 30 days. Among prescription stimulant users without a valid medical prescription, Mann-Whitney U tests and logistic regression analysis revealed that the frequency of energy drink consumption was a significant predictor of illicit prescription stimulant use, with the odds for use increasing by 14% with each additional day of energy drink use (odds ratio for using=1.143, P≤.001). Analyses revealed statistically significant differences (P<.05) between prescription stimulant users and nonusers for all energy drink use variables, with the strongest predictors of prescription stimulant use being the number of days using energy drinks in the past 30 days and number of energy drink binges in the past 30 days. CONCLUSIONS: Results indicate that the frequency of energy drink use was a significant predictor of the illicit use of prescription stimulants.

A comparison of the combined-use of alcohol & energy drinks to alcohol-only on high-risk drinking and driving behaviors.

BACKGROUND: The combined-use of alcohol and energy drinks is an emerging public health issue. This investigation examined differences in drinking and driving behaviors among combined-users (CU) and participants who consumed alcohol-only (AO). OBJECTIVES: This study was specifically designed to investigate potential differences in drinker's perceptions of (a) what it means to them to drive over the .08 Blood Alcohol Content (BAC) driving limit and (b) what it means to drive after knowing they have had too much to drink to drive safely. METHODS: College students (N = 355) were surveyed to assess differences in drinking and driving-related behaviors between the AO (n = 174) and CU (n = 107) groups. RESULTS: CU were more likely than AO to drive over the .08 BAC driving limit (53% vs. 38%; p = .009) and after knowing they were too drunk to drive (57% vs. 44%; p = .025). CU were also more likely (56% vs. 35%; p = .000) to ride with an intoxicated driver while knowing it was unsafe. Conclusions/Importance: Combined-users are more likely to drive after drinking, drive while knowingly drunk, and participate in other high-risk behaviors such as heavy drinking that increase the potential for injury. Public policy makers and health professionals should focus prevention efforts to reduce high-risk combined-use behavior.

Regional body composition in college-aged Caucasians from anthropometric measures.

BACKGROUND: Quantitating fat and lean tissue in isolated body regions may be helpful or required in obesity and health-outcomes research. However, current methods of regional body composition measurement require specialized, expensive equipment such as that used in computed tomography or dual energy x-ray absorptiometry (DEXA). Simple body size or circumference measurement relationships to body composition have been developed but are limited to whole-body applications. We investigated relationships between body size measurements and regional body composition. METHODS: Using DEXA technology we determined the fat and lean tissue composition for six regions of the body in predominantly Caucasian, college-aged men (n = 32) and women (n = 67). Circumference measurements as well as body weight and height were taken for each individual. Equations relating body measurements to a respective regional fat and lean mass were developed using multiple regression analysis. RESULTS: Multiple regression R2 values ranged from 0.4451 to 0.8953 and 0.1697 to 0.7039 for regional fat and lean mass relationships to body measurements, respectively. CONCLUSION: The equations developed in this study offer a simple way of estimating regional body composition in a college-aged adult population. The parameters used in the equations are common body measurements that can be obtained with the use of a measuring tape and weight scale.

Calorie restriction increases the ratio of phosphatidylinositol 3-kinase catalytic to regulatory subunits in rat skeletal muscle.

Calorie restriction [CR; 60% of ad libitum (AL) intake] improves insulin-stimulated glucose transport, concomitant with enhanced phosphorylation of Akt. The mechanism(s) for the CR-induced increase in Akt phosphorylation of insulin-stimulated muscle is unknown. The purpose of this study was to determine whether CR increased the ratio of catalytic to regulatory subunits favoring enhanced phosphatidylinositol (PI) 3-kinase signaling, which may contribute to increases in Akt phosphorylation and glucose transport in insulin-stimulated muscles. We measured the PI 3-kinase regulatory (p85alpha/beta, p50alpha, and p55alpha) and catalytic (p110) subunits abundance in skeletal muscle from male F344B/N rats after 8 wk of AL or CR treatment. In CR compared with AL muscles, regulatory isoforms, p50alpha and p55alpha abundance were approximately 40% lower (P < 0.01) with unchanged p85alpha/beta levels. There was no diet-related change in catalytic subunit abundance. Despite lower IRS-1 levels ( approximately 35%) for CR vs. AL, IRS-1-p110 association in insulin-stimulated muscles was significantly (P < 0.05) enhanced by approximately 50%. Downstream of PI 3-kinase, CR compared with AL significantly enhanced Akt serine phosphorylation by 1.5-fold higher (P = 0.01) and 3-O-methylglucose transport by approximately 20% in muscles incubated with insulin. The increased ratio of PI 3-kinase catalytic to regulatory subunits favors enhanced insulin signaling, which likely contributes to greater Akt phosphorylation and improved insulin sensitivity associated with CR in skeletal muscle.

Brief calorie restriction increases Akt2 phosphorylation in insulin-stimulated rat skeletal muscle.

Skeletal muscle insulin sensitivity improves with short-term reduction in calorie intake. The goal of this study was to evaluate changes in the abundance and phosphorylation of Akt1 and Akt2 as potential mechanisms for enhanced insulin action after 20 days of moderate calorie restriction [CR; 60% of ad libitum (AL) intake] in rat skeletal muscle. We also assessed changes in the abundance of SH2 domain-containing inositol phosphatase (SHIP2), a negative regulator of insulin signaling. Fisher 344 x Brown Norway rats were assigned to an AL control group or a CR treatment group for 20 days. Epitrochlearis muscles were dissected and incubated with or without insulin (500 microU/ml). Total Akt serine and threonine phosphorylation was significantly increased by 32 (P < 0.01) and 30% (P < 0.005) in insulin-stimulated muscles from CR vs. AL. Despite an increase in total Akt phosphorylation, there was no difference in Akt1 serine or Akt1 threonine phosphorylation between CR and AL insulin-treated muscles. However, there was a 30% decrease (P < 0.05) in Akt1 abundance for CR vs. AL. In contrast, there was no change in Akt2 protein abundance, and there was a 94% increase (P < 0.05) in Akt2 serine phosphorylation and an increase of 75% (P < 0.05) in Akt2 threonine phosphorylation of insulin-stimulated CR muscles compared with AL. There was no diet effect on SHIP2 abundance in skeletal muscle. These results suggest that, with brief CR, enhanced Akt2 phosphorylation may play a role in increasing insulin sensitivity in rat skeletal muscles.

Calorie restriction increases muscle insulin action but not IRS-1-, IRS-2-, or phosphotyrosine-PI 3-kinase.

Skeletal muscle insulin sensitivity improves with a moderate reduction in caloric intake. We studied possible mechanisms in calorie-restricted [CR: 60% ad libitum (AL) intake] compared with AL rats, utilizing a time-matched feeding protocol (3, 5, 10, or 20 days). Visceral fat mass was lower for CR vs. AL at 10 and 20 days, but insulin-stimulated muscle 3-O-methylglucose transport was higher in CR vs. AL rats only at 20 days. Fructose 6-phosphate (precursor for the hexosamine biosynthetic pathway, which has inverse relationship with insulin sensitivity) was reduced only at 3 days of CR. Insulin stimulation of insulin receptor substrate (IRS)-1-, IRS-2-, and antiphosphotyrosine-associated phosphatidylinositol 3-kinase (PI3K) was similar for CR and AL. A PI3K inhibitor, wortmannin, reduced insulin-stimulated 3-O-methylglucose transport to basal levels, regardless of diet. With brief time-matched CR, reduced visceral fat mass precedes increased insulin sensitivity; transient reduction in fructose 6-phosphate may trigger more persistent changes but does not coincide with enhanced insulin action; and PI3K is essential for insulin-stimulated 3-O-methylglucose transport in CR as well as AL rats, although insulin-stimulated PI3K is not significantly greater in CR compared with AL animals.