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95 result(s) for "Christian K. Roberts"
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effects of caffeine, nicotine, ethanol, and tetrahydrocannabinol on exercise performance
Caffeine, nicotine, ethanol and tetrahydrocannabinol (THC) are among the most prevalent and culturally accepted drugs in western society. For example, in Europe and North America up to 90% of the adult population drinks coffee daily and, although less prevalent, the other drugs are also used extensively by the population. Smoked tobacco, excessive alcohol consumption and marijuana (cannabis) smoking are addictive and exhibit adverse health effects. These drugs are not only common in the general population, but have also made their way into elite sports because of their purported performance-altering potential. Only one of the drugs (i.e., caffeine) has enough scientific evidence indicating an ergogenic effect. There is some preliminary evidence for nicotine as an ergogenic aid, but further study is required; cannabis and alcohol can exhibit ergogenic potential under specific circumstances but are in general believed to be ergolytic for sports performance. These drugs are currently (THC, ethanol) or have been (caffeine) on the prohibited list of the World Anti-Doping Agency or are being monitored (nicotine) due to their potential ergogenic or ergolytic effects. The aim of this brief review is to evaluate the effects of caffeine, nicotine, ethanol and THC by: 1) examining evidence supporting the ergogenic or ergolytic effects; 2) providing an overview of the mechanism(s) of action and physiological effects; and 3) where appropriate, reviewing their impact as performance-altering aids used in recreational and elite sports.
A High Throughput Biochemical Fluorometric Method for Measuring Lipid Peroxidation in HDL
Current cell-based assays for determining the functional properties of high-density lipoproteins (HDL) have limitations. We report here the development of a new, robust fluorometric cell-free biochemical assay that measures HDL lipid peroxidation (HDLox) based on the oxidation of the fluorochrome Amplex Red. HDLox correlated with previously validated cell-based (r = 0.47, p<0.001) and cell-free assays (r = 0.46, p<0.001). HDLox distinguished dysfunctional HDL in established animal models of atherosclerosis and Human Immunodeficiency Virus (HIV) patients. Using an immunoaffinity method for capturing HDL, we demonstrate the utility of this novel assay for measuring HDLox in a high throughput format. Furthermore, HDLox correlated significantly with measures of cardiovascular diseases including carotid intima media thickness (r = 0.35, p<0.01) and subendocardial viability ratio (r = -0.21, p = 0.05) and physiological parameters such as metabolic and anthropometric parameters (p<0.05). In conclusion, we report the development of a new fluorometric method that offers a reproducible and rapid means for determining HDL function/quality that is suitable for high throughput implementation.
Circulating Levels of Resistin and Risk of Type 2 Diabetes in Men and Women: Results From Two Prospective Cohorts
OBJECTIVE:--The purpose of this study was to investigate the role of circulating resistin levels in the development of type 2 diabetes using two prospective cohorts of well-characterized men and women. RESEARCH DESIGN AND METHODS--We conducted two prospective case-control studies nested in the Women's Health Study (WHS) and Physicians' Health Study II (PHS II). In the WHS, during a median of 10-years of follow-up, 359 postmenopausal women, who were apparently healthy at baseline and later developed type 2 diabetes, were prospectively matched with 359 healthy control subjects. In the PHS II, with 8 years of total follow-up, 170 men, who were apparently healthy at baseline and later developed type 2 diabetes, were matched with 170 healthy control subjects. Control subjects were matched by age, race, and time of blood draw. RESULTS:--Resistin levels at baseline were significantly higher in women than in men (P = 0.003) and in case patients than in control subjects for both women (P < 0.001) and men (P = 0.07). After adjustment for matching factors, physical activity, alcohol intake, smoking, and family history of diabetes, the relative risk of type 2 diabetes comparing the highest to the lowest quartile of resistin in women was 2.22 ([95% CI 1.32-3.73]; Ptrend = 0.002). This association was attenuated after further adjustment for BMI (1.51 [0.86-2.65]; Ptrend = 0.20) or C-reactive protein (1.18 [0.68-2.07]; Ptrend = 0.60). A similar but weaker pattern was observed in men. CONCLUSIONS:--Elevated levels of circulating resistin were significantly related to increased risk of type 2 diabetes, which appears to be partially accounted for by adiposity and the inflammatory process.
Rapid Alterations in Perirenal Adipose Tissue Transcriptomic Networks with Cessation of Voluntary Running
In maturing rats, the growth of abdominal fat is attenuated by voluntary wheel running. After the cessation of running by wheel locking, a rapid increase in adipose tissue growth to a size that is similar to rats that have never run (i.e. catch-up growth) has been previously reported by our lab. In contrast, diet-induced increases in adiposity have a slower onset with relatively delayed transcriptomic responses. The purpose of the present study was to identify molecular pathways associated with the rapid increase in adipose tissue after ending 6 wks of voluntary running at the time of puberty. Age-matched, male Wistar rats were given access to running wheels from 4 to 10 weeks of age. From the 10th to 11th week of age, one group of rats had continued wheel access, while the other group had one week of wheel locking. Perirenal adipose tissue was extracted, RNA sequencing was performed, and bioinformatics analyses were executed using Ingenuity Pathway Analysis (IPA). IPA was chosen to assist in the understanding of complex 'omics data by integrating data into networks and pathways. Wheel locked rats gained significantly more fat mass and significantly increased body fat percentage between weeks 10-11 despite having decreased food intake, as compared to rats with continued wheel access. IPA identified 646 known transcripts differentially expressed (p < 0.05) between continued wheel access and wheel locking. In wheel locked rats, IPA revealed enrichment of transcripts for the following functions: extracellular matrix, macrophage infiltration, immunity, and pro-inflammatory. These findings suggest that increases in visceral adipose tissue that accompanies the cessation of pubertal physical activity are associated with the alteration of multiple pathways, some of which may potentiate the development of pubertal obesity and obesity-associated systemic low-grade inflammation that occurs later in life.
Effect of Aerobic Exercise Training on Arterial Stiffness in Obese Populations
Background and Objective Controversy exists as to whether aerobic exercise training decreases arterial stiffness in obese subjects. The aim of this study was to systematically review and quantify the effect of aerobic exercise training on arterial stiffness in obese populations. Methods MEDLINE, Cochrane, Scopus, and Web of Science were searched up until May 2013 for trials assessing the effect of aerobic training interventions lasting 8 weeks or more on arterial stiffness in obese populations (body mass index ≥30 kg/m 2 ). Standardized mean difference (SMD) in arterial stiffness parameters (augmentation index, β-stiffness, distensibility, pulse wave velocity, arterial waveforms) was calculated using a random-effects model. Subgroup and meta-regression analyses were used to study potential moderating factors. Results Eight trials, comprising a total of 235 subjects with an age range of 49–70 years, met the inclusion criteria. Arterial stiffness was not significantly reduced by aerobic training (SMD −0.17; 95 % confidence interval (CI) −0.39, 0.06, P  = 0.14). Similarly, post-intervention arterial stiffness was similar between the aerobic-trained and control obese groups (SMD 0.02; 95 % CI −0.28, 0.32, P  = 0.88). Neither heterogeneity nor publication bias were detected in these analyses. In subgroup analyses, arterial stiffness was significantly reduced in aerobic-trained subgroups having below median values in post- minus pre-intervention systolic blood pressure (SBP) ( P  < 0.01), exercise intensity rating score ( P  < 0.01), and methodological quality score ( P  < 0.01). Equivalent results were obtained in meta-regression analyses. Conclusion Based on current published trials, arterial stiffness is generally not reduced in middle-aged and older obese populations in response to aerobic training. However, in studies using low-intensity aerobic training and yielding a decrease in SBP, arterial stiffness may decrease. Long-term studies are needed to assess the prognostic value of these findings.
Immigration Disparities in Cardiovascular Disease Risk Factor Awareness
The association between immigration status and cardiovascular disease (CVD) risk factor awareness is unknown. Using physical examination-based data and participants’ self-report of prior diagnosis, we assessed immigration-based disparities in awareness of diabetes, hypertension, hypercholesterolemia, and overweight among 12,124 participants in the 2003–2008 National Health and Nutrition Examination Survey. Unawareness of CVD risk factors is high among all groups, but tends to be higher among foreign-born English and non-English speaking participants than among US-born participants. After adjusting for demographic factors and access to health care, foreign-born participants appear more likely to be unaware of their hypertension and overweight than US-born participants. Immigrants are more likely than those born in the US to be unaware of their CVD risk factors, and therefore may be less motivated to seek treatment and modify their behavior to prevent negative CVD outcomes.
Characterization of Intra-myocellular Lipids using 2D Localized Correlated Spectroscopy and Abdominal Fat using MRI in Type 2 Diabetes
A major goal of this pilot study was to quantify intramyocellular lipids (IMCL), extra-myocellular lipids (EMCL), unsaturation index (UI) and metabolites such as creatine (Cr), choline (Ch) and carnosine (Car), in the soleus muscle using two-dimensional (2D) localized correlated spectroscopy (L-COSY). Ten subjects with type 2 diabetes (T2D), controlled by lifestyle management alone, and 9 healthy control subjects, were studied. In T2D patients only, the following measurements were obtained: body mass index (BMI); waist circumference (WC); abdominal visceral and subcutaneous fat quantified using breath-held magnetic resonance imaging (MRI); a fasting blood draw for assessment of glucose, insulin, and estimation of homeostasis model assessment of insulin resistance (HOMA-IR), HbA1c, and high-sensitivity c-reactive protein (hs-CRP). Analysis of the soleus muscle 2D L-COSY spectral data showed significantly elevated IMCL ratios with respect to Cr and decreased IMCL UI in T2D when compared to healthy subjects (P < 0.05). In T2D subjects, Pearson correlation analysis showed a positive correlation of IMCL/Cr with EMCL/Cr (0.679, P < 0.05) and HOMA-IR (0.633, P < 0.05), and a non-significant correlation of visceral and subcutaneous fat with magnetic resonance spectroscopy (MRS) and other metrics. Characterization of muscle IMCL and EMCL ratios, UI, and abdominal fat, may be useful for the noninvasive assessment of the role of altered lipid metabolism in the pathophysiology of T2D, and for assessment of the effects of future therapeutic interventions designed to alter metabolic dysfunction in T2D.
Combined diet and exercise interventions can improve metabolic outcomes in obese children, even with only small changes in weight
The addition of exercise training to dietary interventions resulted in modest improvements in high-density lipoprotein cholesterol (HDL-C) (pooled difference 3.86 mg/dL, 95% CI 2.7 to 4.63) and glycaemic-control-related variables including glucose (pooled difference -2.16 mg/dL, 95% CI -3.78 to -0.72) and insulin (pooled difference -2.75, 95% CI -4.50 to -1.00). Another study recently demonstrated that a short-term, intensive lifestyle modification programme ameliorated metabolic risk factors similarly in normal weight and obese children. 6 These results suggested that obesity per se was unlikely to be the primary driver of the phenotypes noted; dietary intake and physical inactivity induce the phenotypic abnormalities, and are potentially correctable with intensive lifestyle modification.
Elevated liver enzymes in individuals with undiagnosed diabetes in the U.S
We investigated the association of diabetes diagnosis and medication type with liver injury in individuals with clinical diabetes. We analyzed 2426 patients with clinical diabetes in the National Health and Nutrition Examination Survey conducted from 1999 to 2008. Elevated alanine transaminase (ALT) and aspartate transaminase (AST) levels were used as markers of liver injury. Participants were categorized into one of three categories: 1) clinical diabetes without physician’s diagnosis or diabetes medication; 2) diagnosed diabetes without diabetes medication; or 3) diagnosed diabetes with diabetes medication, further divided by classes of diabetes medications prescribed. We conducted logistic regression analysis to examine the relationship between diabetes diagnosis and medication type and elevated ALT and AST, adjusting for race/ethnicity, education, health insurance status, BMI category, alcohol consumption, physical activity, antihyperlipidemic agents, glycohemoglobin, C-reactive protein, viral hepatitis and liver disease. Participants with undiagnosed diabetes were more likely to have elevated ALT and AST levels (OR=1.82, 95% CI 1.47, 2.42; OR=1.99, 95% CI 1.46, 2.71, respectively). In contrast, there was no association between specific diabetes medication (i.e., sulfonylureas, biguanides/thiazolidinediones) and elevated ALT or AST levels among the treated. Our findings were confirmed in sensitivity analyses employing a lower threshold for ALT, and excluding individuals with viral hepatitis or liver disease. We found that undiagnosed diabetes is associated with liver injury, compared to diagnosed diabetes with treatment. The effect of diabetes treatment on liver injury in individuals with diabetes remains uncertain.
Training the Next Generation of Latino Health Researchers
Reducing health disparities is a national public health priority. Latinos represent the largest racial/ethnic minority group in the United States and suffer disproportionately from poor health outcomes, including cardiovascular disease risk. Academic training programs are an opportunity for reducing health disparities, in part by increasing the diversity of the public health workforce and by incorporating training designed to develop a skill set to address health disparities. This article describes the Training and Career Development Program at the UCLA Center for Population Health and Health Disparities: a multilevel, transdisciplinary training program that uses a community-engaged approach to reduce cardiovascular disease risk in two urban Mexican American communities. Results suggest that this program is effective in enhancing the skill sets of traditionally underrepresented students to become health disparities researchers and practitioners.