BMI and seatbelt use

Objective: Seatbelt use among obese persons may be reduced because seatbelts are uncomfortable. We investigated the association between obesity and seatbelt use with data from the 2002 Behavioral Risk Factor Surveillance System Survey. Research Methods and Procedures: Multivariable logistic regression was used to calculate odds ratios and 95% confidence intervals (CIs) for seatbelt use among overweight (BMI, 25.0 to 29.9), obese (BMI, 30.0 to 39.9), and extremely obese (BMI ≥ 40.0) persons, relative to a non‐overweight/non‐obese reference group (BMI ≤ 24.9), adjusted for age, race, gender, education, and state seatbelt law. Results: Adjusted odds ratios for seatbelt use were 0.89 (95% CI, 0.85 to 0.93) for overweight, 0.69 (0.66 to 0.73) for obese, and 0.45 (95% CI, 0.40 to 0.50) for extremely obese persons. Interaction effects were evident for all covariates, with stronger associations between increasing BMI and decreasing seatbelt use for women, increasing age, higher education, and residence in states with a secondary seatbelt law. There was a linear decrease in seatbelt use with increasing BMI for all subgroups except persons 18 to 24 years old. Discussion: Lack of seatbelt can be added to the list of risk factors associated with obesity. Effective preventive interventions are needed to promote seatbelt use among overweight and obese persons.     

The impact of confounders on the test performance of natriuretic peptides for cardiac dysfunction in subjects aged 80 and older

The hypothesis that natriuretic peptides could be used to identify ‘pancardiac’ damage has been proposed. However, multiple factors are known to influence circulating levels of natriuretic peptides, especially in the very old. Therefore, the impact of confounders on the association between natriuretic peptide levels and cardiac dysfunction was further explored in subjects aged 80 and older. A diagnostic cross-sectional study embedded within the BELFRAIL study (n = 567) was performed. Baseline BNP and NT-proBNP levels were measured and echocardiograms were performed at the subject's home. Cardiac dysfunction was defined as systolic dysfunction, valvular heart disease or isolated severe diastolic dysfunction. Several functional and structural echocardiographic parameters were independently related to circulating levels of natriuretic peptides. Cystatin C, BMI, β blockers, diabetes, heart frequency, usCRP, age and sex were identified as confounders. The prevalence of cardiac dysfunction was 17.1% in the subjects without and 30.8% in the subjects with chronic atrial fibrillation (CAF) or pacemaker (PM). Only in subjects with CAF or PM the C statistic for cardiac dysfunction improved after correcting for confounders. The post-test probability for a negative test (PTP−) ranged from 3.7% to 12.2% and the PTP+ ranged from 21.9% to 62.2% in different strata of confounders. According to these data adjusting for identified confounders does not improve the diagnostic accuracy of the natriuretic peptides for cardiac dysfunction, except in subjects with CAF or PM. Stratifying for individual confounders showed that different cut-off values could be used to optimize the diagnostic characteristics of natriuretic peptides.     

Oncoprotein BMI‐1 induces the malignant transformation of HaCaT cells

BMI‐1 (B‐cell‐specific Moloney murine leukemia virus integration site 1), a novel oncogene, has attracted much attention in recent years for its involvement in the initiation of a variety of tumors. Recent evidence showed that BMI‐1 was highly expressed in neoplastic skin lesions. However, whether dysregulated BMI‐1 expression is causal for the transformation of skin cells remains unknown. In this study, we stably expressed BMI‐1 in a human keratinocyte cell line, HaCaT. The expression of wild‐type BMI‐1 induced the malignant transformation of HaCaT cells in vitro. More importantly, we found that expression of BMI‐1 promoted formation of squamous cell carcinomas in vivo. Furthermore, we showed that BMI‐1 expression led to the downregulation of tumore suppressors, such as p16INK4a and p14ARF, cell adhesion molecules, such as E‐Cadherin, and differentiation related factor, such as KRT6. Therefore, our findings demonstrated that dysregulated BMI‐1 could indeed lead to keratinocytes transformation and tumorigenesis, potentially through promoting cell cycle progression and increasing cell mobility. J. Cell. Biochem. 106: 16–24, 2009. © 2008 Wiley‐Liss, Inc.     

A review on directional information in neural signals for brain-machine interfaces

Brain-machine interfaces (BMIs) can be characterized by the technique used to measure brain activity and by the way different brain signals are translated into commands that control an effector. We give an overview of different approaches and focus on a particular BMI approach: the movement of an artificial effector (e.g. arm prosthesis to the right) by those motor cortical signals that control the equivalent movement of a corresponding body part (e.g. arm movement to the right). This approach has been successfully applied in monkeys and humans by accurately extracting parameters of movements from the spiking activity of multiple single-units. Here, we review recent findings showing that analog neuronal population signals, ranging from intracortical local field potentials over epicortical ECoG to non-invasive EEG and MEG, can also be used to decode movement direction and continuous movement trajectories. Therefore, these signals might provide additional or alternative control for this BMI approach, with possible advantages due to reduced invasiveness.     

Rapid down-regulation of mitochondrial fat metabolism in human muscle after training cessation is dissociated from changes in insulin sensitivity

The association between impairment in mitochondrial muscle fat oxidative capacity (OX_FA) and occurrence of insulin resistance was examined in 14 healthy trained men (age, 24 ± 4 yr) submitted to 4 weeks of training cessation. Training stop induced a significant decrease in mRNA levels of proteins involved in muscle fat metabolism, particularly PPARα (−58%, P < 0.01) and PGC-1α (−30%, P < 0.05), a 21% reduction in OX_FA (P < 0.01), and reduced fat oxidation during moderately intense exercise (P < 0.05). In contrast, there was no significant alteration in insulin sensitivity. In conclusion, decline in OX_FA is a rapid metabolic event following training cessation. It is involved in the regulation of whole body fat balance but not in the deterioration of insulin sensitivity.     

Dose-dependent effects of training and detraining on weight in 6406 runners during 7.4 years

Objective: Prior randomized and non‐randomized training studies have failed to establish a dose‐response relationship between vigorous exercise and weight loss; this failure may be due, in part, to their short durations and small sample sizes. The objectives of this study were to determine whether exercise reduces body weight and to examine the dose‐response relationships between changes in exercise and changes in total and regional adiposity. Research Methods and Procedures: This was a large prospective study of 3973 men and 1444 women who quit running (detraining), 270 men and 146 women who started running (training), and 420 men and 153 women who remained sedentary during 7.4 years of follow‐up. The outcomes measured were weekly running distance, body weight, BMI, body circumferences, and bra cup size. Results: There were significant inverse relationships between the changes in the amount of vigorous exercise (km/wk run) and the changes in weight and BMI in men (slope ± standard error: ?0.039 ± 0.005 kg/km per week and ?0.012 ± 0.002 kg/m² per km/wk, respectively) and in older women (?0.060 ± 0.018 kg/km per week and ?0.022 ± 0.007 kg/m² per km/wk) who quit running, and in initially sedentary men (?0.098 ± 0.017 kg/km per week and ?0.032 ± 0.005 kg/m² per km/wk) and women (?0.062 ± 0.023 kg/km per week and ?0.021 ± 0.008 kg/m² per km/wk) who started running. Changes in waist circumference, an indicator of intra‐abdominal fat, were also inversely related to changes in running distance in men who quit (?0.026 ± 0.005 cm/km per week) or started running (?0.078 ± 0.017 cm/km per week). Discussion: The initiation of vigorous exercise and its cessation decrease and increase, respectively, body weight and intra‐abdominal fat, and these changes are proportional to the change in exercise dose.     

Confronting and coping with weight stigma: an investigation of overweight and obese adults

Objective: This study examined experiences of weight stigmatization, sources of stigma, coping strategies, psychological functioning, and eating behaviors in a sample of 2671 overweight and obese adults. Research Methods and Procedures: The total sample was partitioned into two subsamples for investigation. Sample I was comprised of 2449 adult women, and Sample II was a matched sample of adult men and women (N = 222) that was disaggregated to investigate gender differences. Both samples completed an online battery of self‐report questionnaires measuring frequency of weight stigmatization and coping responses to deal with bias, the most common sources of the bias, symptoms of depression, self‐esteem, attitudes about weight and obesity, and binge eating behaviors. Results: Experiences of weight stigmatization, in many forms and across multiple occasions, was common in both samples. A variety of coping strategies were used in response. More frequent exposure to stigma was related to more attempts to cope and higher BMI. Physicians and family members were the most frequent sources of weight bias reported. No gender differences were observed in types or frequency of stigmatization. Frequency of stigmatization was not related to current psychological functioning, although coping responses were associated with emotional well‐being. Discussion: These findings raise questions about the relationship between stigma and psychological functioning and have important implications for obesity treatment and stigma reduction intervention efforts, both of which are discussed.     

Retinal vessel diameters and obesity: a population-based study in older persons

Objective: Obesity is linked with large vessel atherosclerosis and diabetes. Its association with microvascular changes is less clear. We investigated the associations among retinal vessel diameters, vessel wall signs, and BMI in an older population. Research Methods and Procedures: Retinal photographs were taken on 3654 persons aged 49+ years at baseline of the Blue Mountains Eye Study in Australia. Arteriolar and venular diameters were measured from digitized retinal photographs of the right eyes. BMI was calculated as weight (kilograms)/height (meters²). Incident obesity was defined in persons with BMI ≤ 30 at baseline but >30 after 5 years. A significant weight gain was defined as an increase in BMI of 2+ SDs (4 or more units) over the 5‐year period. Results: At baseline, mean BMI was 26.1 (±4.6) in this population. At 5‐year examinations, 177 (10.0% of 1773 at risk) developed incident obesity, and 136 (6.4% of 2143 at risk) had significant weight gain. After adjusting for age, sex, smoking, triglyceride levels, and mean arterial blood pressure, persons with wider retinal venular diameters had a higher risk of incident obesity (odds ratio, 1.8; 95% confidence interval, 1.0 to 3.1, comparing the highest with lowest venular diameter quintiles) and significant weight gain (odds ratio, 1.7; 95% confidence interval, 0.9 to 3.2). These associations were attenuated with further adjustment for baseline BMI. Arteriolar diameter was unrelated with baseline or change in BMI. Discussion: Wider retinal venular diameter is associated with risk of obesity, independent of hypertension, diabetes, lipids, and cigarette smoking. These data may support a role for impaired microvascular function in the course of weight gain.     

Obesity is a risk factor for reporting homebound status among community-dwelling older persons

Objective : To test the a priori hypothesis that obesity is a predictor of risk for reporting homebound status. Research Methods and Procedures : A longitudinal cohort study was conducted with 21, 645 community‐dwelling men and women 65 to 97 years old. A nutrition risk screen was administered baseline between 1994 and 1999 and again 3 to 4 years later. Univariate analyses identified baseline variables associated with subsequent reporting of homebound status. Multivariable logistic regression models were created to identify baseline variables that were significant independent predictors of reporting homebound status. Results : At baseline, 24% of the cohort had BMI ≥ 30. There were 12, 834 (45% men) respondents at follow‐up (68% response). Non‐responders at follow‐up differed little from responders except for greater baseline age (72.2 ± 6.2 vs. 71.4 ± 5.6 years, p < 0.001) and reporting of any functional limitations (9.2% vs. 4.9%, p < 0.001). At follow‐up, those who reported homebound status (n = 169) were significantly (p < 0.001) older (80.3 ± 7.3 vs. 75.1 ± 5.5 years) and more likely to report functional limitations (83.4% vs. 10.8%). Univariate analyses identified 16 baseline variables that were eliminated stepwise until five significant independent predictors remained: age ≥ 75 years (2.21, 1.55 to 3.15/odds ratio, 95% confidence interval), BMI ≥ 35 (1.75, 1.04 to 2.96), poor appetite (2.50, 1.29 to 4.86), low income (1.59, 1.00 to 2.56), and any functional limitation (10.67, 7.36 to 15.46). Discussion : Obesity remained a significant independent predictor for reporting homebound status and should be considered in screening of older populations and in the planning, implementation, and evaluation of services for homebound older persons.     

Serum phospholipid fatty acids, adipose tissue, and metabolic markers in obese adolescents

Objective: Fatty acid (FA) composition has a role in adipogenesis. The objective was to study serum phospholipid (PL) FAs in adolescents and their relation to abdominal adipose tissue (AT) compartments and metabolic markers. Research Methods and Procedures: Abdominal AT was measured by magnetic resonance imaging and FA pattern was determined in serum PL of 10 obese adolescents (5 females), median age 12.0 years (range, 10.4 to 16.4) and BMI 30.7 (26.8 to 40.4), and 15 lean control subjects (9 females), median age 12.6 years (range, 11.3 to 15.4), and BMI 19.5 (17.1 to 23.4). Results: Obese adolescents had relatively higher levels of saturated FA (SFA) and nervonic acid compared with controls. Serum PL concentration of n‐3 polyunsaturated fatty acids (PUFA) was lower in the obese vs. lean females (p = 0.01), including docosahexaenoic acid (DHA) (p = 0.01). The ratios of arachidonic acid to DHA and total n‐6/n‐3 FA were increased in obese children (p = 0.02 and 0.01, respectively). n‐3 PUFAs were inversely correlated to all subcutaneous AT compartments except visceral AT. The homeostasis model assessment index of β‐cell function related inversely to DHA concentration (p = 0.03). All changes were more marked in the females. Discussion: Serum FA pattern in obese adolescents differed significantly from that in age‐matched lean controls, reflecting a decrease in n‐3 PUFA, especially DHA, and an increase in SFA. The subcutaneous AT, but not visceral AT, correlated to the changes in PUFA and SFA, suggesting an abnormal essential FA metabolism in obese adolescents.