Bidirectional relationship between the Body Mass Index and Substance Use in Young Men

BACKGROUND: Obesity and substance use are major concern in young people. This study explored the bidirectional longitudinal relationships between the body mass index (BMI) of young men and their use of: 1) four classes of non-medical prescription drugs; 2) alcohol; 3) tobacco; and 4) cannabis. METHODS: Baseline and follow-up data from the Cohort Study on Substance Use Risk Factors were used (n=5,007). A cross-lagged panel model, complemented by probit models as sensitivity analysis, was run to determine the bidirectional relationships between BMI and substance use. Alcohol was assessed using risky single-occasion drinking (RSOD); tobacco, using daily smoking; and cannabis, using hazardous cannabis use (defined as twice-weekly or more cannabis use). Non-medical prescription drugs use (NMPDU) included opioid analgesics, sedatives/sleeping pills, anxiolytics and stimulants. RESULTS: Different associations were found between BMI and substance use. Only RSOD (β= -.053, p=.005) and NMPDU of anxiolytics (β=.040, p=.020) at baseline significantly predicted BMI at follow-up. Baseline RSOD predicted a lower BMI at follow-up while baseline NMPDU of anxiolytics predicted higher BMI at follow-up. Furthermore, BMI at baseline significantly predicted daily smoking (β=.050, p=.007) and hazardous cannabis use (β=.058, p=.030). CONCLUSIONS: Our results suggest different associations between BMI and the use of various substances by young men. However, only RSOD and NMPDU of anxiolytics predicted BMI, whereas BMI predicted daily smoking and hazardous cannabis use.

Fast and sensitive supercritical fluid chromatography - tandem mass spectrometry multi-class screening method for the determination of doping agents in urine.

This study shows the possibility offered by modern ultra-high performance supercritical fluid chromatography combined with tandem mass spectrometry in doping control analysis. A high throughput screening method was developed for 100 substances belonging to the challenging classes of anabolic agents, hormones and metabolic modulators, synthetic cannabinoids and glucocorticoids, which should be detected at low concentrations in urine. To selectively extract these doping agents from urine, a supported liquid extraction procedure was implemented in a 48-well plate format. At the tested concentration levels ranging from 0.5 to 5 ng/mL, the recoveries were better than 70% for 48-68% of the compounds and higher than 50% for 83-87% of the tested substances. Due to the numerous interferences related to isomers of steroids and ions produced by the loss of water in the electrospray source, the choice of SFC separation conditions was very challenging. After careful optimization, a Diol stationary phase was employed. The total analysis time for the screening assay was only 8 min, and interferences as well as susceptibility to matrix effect (ME) were minimized. With the developed method, about 70% of the compounds had relative ME within the range ±20%, at a concentration of 1 and 5 ng/mL. Finally, limits of detection achieved with the above-described strategy including 5-fold preconcentration were below 0.1 ng/mL for the majority of the tested compounds. Therefore, LODs were systematically better than the minimum required performance levels established by the World anti-doping agency, except for very few metabolites.

Trends in adult body-mass index in 200 countries from 1975 to 2014: a pooled analysis of 1698 population-based measurement studies with 19·2 million participants.

BACKGROUND: Underweight and severe and morbid obesity are associated with highly elevated risks of adverse health outcomes. We estimated trends in mean body-mass index (BMI), which characterises its population distribution, and in the prevalences of a complete set of BMI categories for adults in all countries. METHODS: We analysed, with use of a consistent protocol, population-based studies that had measured height and weight in adults aged 18 years and older. We applied a Bayesian hierarchical model to these data to estimate trends from 1975 to 2014 in mean BMI and in the prevalences of BMI categories (<18·5 kg/m(2) [underweight], 18·5 kg/m(2) to <20 kg/m(2), 20 kg/m(2) to <25 kg/m(2), 25 kg/m(2) to <30 kg/m(2), 30 kg/m(2) to <35 kg/m(2), 35 kg/m(2) to <40 kg/m(2), ≥40 kg/m(2) [morbid obesity]), by sex in 200 countries and territories, organised in 21 regions. We calculated the posterior probability of meeting the target of halting by 2025 the rise in obesity at its 2010 levels, if post-2000 trends continue. FINDINGS: We used 1698 population-based data sources, with more than 19·2 million adult participants (9·9 million men and 9·3 million women) in 186 of 200 countries for which estimates were made. Global age-standardised mean BMI increased from 21·7 kg/m(2) (95% credible interval 21·3-22·1) in 1975 to 24·2 kg/m(2) (24·0-24·4) in 2014 in men, and from 22·1 kg/m(2) (21·7-22·5) in 1975 to 24·4 kg/m(2) (24·2-24·6) in 2014 in women. Regional mean BMIs in 2014 for men ranged from 21·4 kg/m(2) in central Africa and south Asia to 29·2 kg/m(2) (28·6-29·8) in Polynesia and Micronesia; for women the range was from 21·8 kg/m(2) (21·4-22·3) in south Asia to 32·2 kg/m(2) (31·5-32·8) in Polynesia and Micronesia. Over these four decades, age-standardised global prevalence of underweight decreased from 13·8% (10·5-17·4) to 8·8% (7·4-10·3) in men and from 14·6% (11·6-17·9) to 9·7% (8·3-11·1) in women. South Asia had the highest prevalence of underweight in 2014, 23·4% (17·8-29·2) in men and 24·0% (18·9-29·3) in women. Age-standardised prevalence of obesity increased from 3·2% (2·4-4·1) in 1975 to 10·8% (9·7-12·0) in 2014 in men, and from 6·4% (5·1-7·8) to 14·9% (13·6-16·1) in women. 2·3% (2·0-2·7) of the world's men and 5·0% (4·4-5·6) of women were severely obese (ie, have BMI ≥35 kg/m(2)). Globally, prevalence of morbid obesity was 0·64% (0·46-0·86) in men and 1·6% (1·3-1·9) in women. INTERPRETATION: If post-2000 trends continue, the probability of meeting the global obesity target is virtually zero. Rather, if these trends continue, by 2025, global obesity prevalence will reach 18% in men and surpass 21% in women; severe obesity will surpass 6% in men and 9% in women. Nonetheless, underweight remains prevalent in the world's poorest regions, especially in south Asia. FUNDING: Wellcome Trust, Grand Challenges Canada.

Ideal Body Size as a Mediator for the Gender-Specific Association Between Socioeconomic Status and Body Mass Index: Evidence From an Upper-Middle-Income Country in the African Region.

While obesity continues to rise globally, the associations between body size, gender, and socioeconomic status (SES) seem to vary in different populations, and little is known on the contribution of perceived ideal body size in the social disparity of obesity in African countries. We examined the gender and socioeconomic patterns of body mass index (BMI) and perceived ideal body size in the Seychelles, a middle-income small island state in the African region. We also assessed the potential role of perceived ideal body size as a mediator for the gender-specific association between SES and BMI. A population-based survey of 1,240 adults aged 25 to 64 years conducted in December 2013. Participants' BMI was calculated based on measured weight and height; ideal body size was assessed using a nine-silhouette instrument. Three SES indicators were considered: income, education, and occupation. BMI and perceived ideal body size were both higher among men of higher versus lower SES (p< .001) but lower among women of higher versus lower SES (p< .001), irrespective of the SES indicator used. Multivariate analysis showed a strong and direct association between perceived ideal body size and BMI in both men and women (p< .001) and was consistent with a potential mediating role of perceived ideal body size in the gender-specific associations between SES and BMI. Our study emphasizes the importance of gender and socioeconomic differences in BMI and ideal body size and suggests that public health interventions that promote perception of healthy weight could help mitigate SES-related disparities in BMI.

Similar Hemoglobin Mass Response in Hypobaric and Normobaric Hypoxia in Athletes

PURPOSE: To compare hemoglobin mass (Hbmass) changes during an 18-d live high-train low (LHTL) altitude training camp in normobaric hypoxia (NH) and hypobaric hypoxia (HH). METHODS: Twenty-eight well-trained male triathletes were split into three groups (NH: n = 10, HH: n = 11, control [CON]: n = 7) and participated in an 18-d LHTL camp. NH and HH slept at 2250 m, whereas CON slept, and all groups trained at altitudes <1200 m. Hbmass was measured in duplicate with the optimized carbon monoxide rebreathing method before (pre-), immediately after (post-) (hypoxic dose: 316 vs 238 h for HH and NH), and at day 13 in HH (230 h, hypoxic dose matched to 18-d NH). Running (3-km run) and cycling (incremental cycling test) performances were measured pre and post. RESULTS: Hbmass increased similar in HH (+4.4%, P < 0.001 at day 13; +4.5%, P < 0.001 at day 18) and NH (+4.1%, P < 0.001) compared with CON (+1.9%, P = 0.08). There was a wide variability in individual Hbmass responses in HH (-0.1% to +10.6%) and NH (-1.4% to +7.7%). Postrunning time decreased in HH (-3.9%, P < 0.001), NH (-3.3%, P < 0.001), and CON (-2.1%, P = 0.03), whereas cycling performance changed nonsignificantly in HH and NH (+2.4%, P > 0.08) and remained unchanged in CON (+0.2%, P = 0.89). CONCLUSION: HH and NH evoked similar Hbmass increases for the same hypoxic dose and after 18-d LHTL. The wide variability in individual Hbmass responses in HH and NH emphasizes the importance of individual Hbmass evaluation of altitude training.

From Regional Landslide Detection to Site-Specific Slope Deformation Monitoring and Modelling Based on Active Remote Sensors

Landslide processes can have direct and indirect consequences affecting human lives and activities. In order to improve landslide risk management procedures, this PhD thesis aims to investigate capabilities of active LiDAR and RaDAR sensors for landslides detection and characterization at regional scales, spatial risk assessment over large areas and slope instabilities monitoring and modelling at site-specific scales. At regional scales, we first demonstrated recent boat-based mobile LiDAR capabilities to model topography of the Normand coastal cliffs. By comparing annual acquisitions, we validated as well our approach to detect surface changes and thus map rock collapses, landslides and toe erosions affecting the shoreline at a county scale. Then, we applied a spaceborne InSAR approach to detect large slope instabilities in Argentina. Based on both phase and amplitude RaDAR signals, we extracted decisive information to detect, characterize and monitor two unknown extremely slow landslides, and to quantify water level variations of an involved close dam reservoir. Finally, advanced investigations on fragmental rockfall risk assessment were conducted along roads of the Val de Bagnes, by improving approaches of the Slope Angle Distribution and the FlowR software. Therefore, both rock-mass-failure susceptibilities and relative frequencies of block propagations were assessed and rockfall hazard and risk maps could be established at the valley scale. At slope-specific scales, in the Swiss Alps, we first integrated ground-based InSAR and terrestrial LiDAR acquisitions to map, monitor and model the Perraire rock slope deformation. By interpreting both methods individually and originally integrated as well, we therefore delimited the rockslide borders, computed volumes and highlighted non-uniform translational displacements along a wedge failure surface. Finally, we studied specific requirements and practical issues experimented on early warning systems of some of the most studied landslides worldwide. As a result, we highlighted valuable key recommendations to design new reliable systems; in addition, we also underlined conceptual issues that must be solved to improve current procedures. To sum up, the diversity of experimented situations brought an extensive experience that revealed the potential and limitations of both methods and highlighted as well the necessity of their complementary and integrated uses.

Keeping the balance? Management of oxidative stress, body mass and reproduction under energetic constraints by dispersing and philopatric collared flycatchers.

Dispersal, i.e. individual movement between breeding sites, is a key process for metapopulation dynamics and gene flow. Its success can be modulated by phenotypic differences between dispersing and philopatric individuals, or dispersal syndromes. However, the environmental (external) and physiological (internal) constraints underlying such syndromes remain poorly known. This project aimed at clarifying the impact of environmental variation and oxidative constraints, linked to the reactive oxygen species produced during respiration, on phenotypes associated to dispersal in a passerine bird, the collared flycatcher Ficedula albicollis. Energetic demand was experimentally (i) increased through a wing load manipulation or (ii) relieved through food supplementation. The oxidative balance of breeding flycatchers was influenced by complex interactions of dispersal status and extrinsic factors (breeding density, year, experimental treatments). Interestingly, antioxidant capacity was influenced both by permanent individual differences and by food availability, whereas measures of pro-oxidants were highly variables within individuals. Environmental variation and energetic constraints also modulated the differences in reproduction associated with dispersal: dispersing and philopatric birds differ in their management of the oxidative balance when it is competing with reproductive investment. This thesis highlights that reaction norms, rather than fixed differences, often shape traits associated to dispersal. ----- Le déplacement d'un individu entre sites de reproduction, ou dispersion, est un processus clé pour la dynamique des métapopulations et les flux de gènes. Son succès peut être modulé par des différences de phénotype, ou syndromes de dispersion. Cependant, les contraintes environnementales et physiologiques qui sous-tendent ces syndromes restent mal connues. Ce projet vise à clarifier l'impact des variations environnementales et des contraintes oxydatives (liées aux espèces réactives de l'oxygène produites durant la respiration) sur les phénotypes associés à la dispersion chez un passereau, le gobemouche à collier Ficedula albicollis. La demande énergétique a été expérimentalement (i) augmentée en manipulant la surface alaire ou (ii) diminuée par une supplémentation en nourriture. L'équilibre oxydo-réducteur des gobemouches en reproduction est influencé par des interactions complexes entre statut de dispersion et facteurs extrinsèques (densité de couples reproducteurs, année, traitement expérimental). La capacité antioxydante dépend principalement de différences permanentes entre individus, alors que les pro-oxydants présentent de grandes variations intra-individu. Environnement et contraintes énergétiques modulent aussi les différences de reproduction liées à la dispersion : les oiseaux dispersants et philopatriques diffèrent dans leur gestion de l'équilibre oxydo-réducteur lorsqu'il est en compétition avec l'investissement reproducteur. Ce travail souligne que les traits associés à la dispersion sont souvent déterminés par des normes de réaction à l'environnement et non des différences fixées entre individus.