Lower adiponectin is associated with higher anthropometry and insulin resistance but not with low cardiorespiratory fitness in adolescents

PURPOSE

The aim of this study was to analyze the relationship between adiposity, cardiometabolic risk and cardiorespiratory fitness (CRF) according to different groups of adiponectin concentration.

METHODS

255 adolescents of both sexes, aged 11-17 years old, participated. Anthropometric and biochemical parameters such as body mass, height, abdominal circumference (AC), waist circumference (WC), fat mass, fat-free mass, total cholesterol (TC), high-density lipoprotein (HDL-c), low-density lipoprotein (LDL-c), triglycerides (TG), glucose, insulin, adiponectin, blood pressure, peak oxygen consumption (VO2peak) were measured. Body mass index (BMI), z-score BMI (BMI-z), triponderal mass index (TMI), waist-to-height ratio (WHtR), homeostasis model to assessment insulin resistance (HOMA-IR), and quantitative insulin sensitivity check index (QUICKI) were calculated. Adiponectin was categorized: low adiponectin concentration (LAC  ≤ 5.18 µg/mL-1), intermediate (IAC = 5.18 and 7.63 µg/mL-1) and high (HAC ≥ 7.63 µg/ml-1).

RESULTS

LAC showed higher BMI, BMI-z and TMI than the other groups (p < 0.05) and higher AC, WC and WHtR that the HAC (p < 0.05). IAC showed lower values of TC, LDL-c and TG, and the LAC presented the highest values of insulin, HOMA-IR and QUICKI (p < 0.05) to the IAC and HAC. HAC presented the lower VO2peak than the other groups (p < 0.01). BMI, TMI, glucose, insulin, HOMA-IR showed inverse, and QUICKI a direct and weak correlation with adiponectin (p < 0.05). No significant association was found between adiponectin and VO2peak (p > 0.05).

CONCLUSION

The LAC group had higher means in the anthropometric variables and the worst results related to insulin resistance and sensitivity. Thus, adiponectin may play an important role in obesity and reduced concentration may be a factor in the development of obesity-associated morbidities.

Responsiveness on metabolic syndrome criteria and hepatic parameters after 12 weeks and 24 weeks of multidisciplinary intervention in overweight adolescents

PURPOSE

This study aimed to evaluate the effect and individual responsiveness after 12 (12wk) and 24 weeks (24wk) of physical exercise (PE) and nutritional guidance (NG) on metabolic syndrome (MetS) criteria and hepatic parameters in overweight adolescents.

METHODS

The study comprised 94 overweight adolescents, aged between 10 and 16 years old, from both sexes, allocated into groups: PE and NG (PENGG, n = 64) and control with NG (NGCG, n = 30). Variables were collected at baseline, 12wk, and 24wk. Weight, height, abdominal circumference (AC), blood pressure, and peak oxygen consumption (VO_2peak), as well as insulin, triglycerides (TAG), high-density lipoprotein (HDL-c), aspartate aminotransferase (AST) and alanine aminotransferase (ALT) were evaluated. HOMA-IR and QUICKI were calculated. PE session consisted of 45 min of indoor cycling, 45 min of walking, and 20 min of stretching, three times a week. The NG consisted of three collective sessions in the first 12wk. Anova, effect size, and prevalence of responders were used for statistical analysis.

RESULTS

The PENGG12wk reduced anthropometric and metabolic measurements, while increased VO_2peak and HDL-c. The PEG24wk promoted anthropometric, blood pressure, metabolic, and VO_2peak improvements, but participants without PE returned to pre-exercise status and presented worsening AST and ALT concentrations. Frequencies of respondents in PENGG12wk versus (vs) NGCG12wk were, respectively, AC (69.1% vs 17.6%, p < 0.01), HDL-c (87.2% vs 23.5%, p < 0.01), TAG (67.3% vs 41.7%, p = 0.05) and ALT (45.5% vs 5,9%; p = 0.003).

CONCLUSION

Interventions with PE were effective to reduce MetS components in 12wk and maintenance in 24wk, showing anthropometric, metabolic, and VO_2peak improvements. Higher individual responses were observed in 12wk and in 24wk, important changes in overweight adolescent's therapy.

LEVEL OF EVIDENCE

Level I, evidence obtained from well-designed controlled trials randomization.

TRIAL REGISTRATION NUMBER AND DATE OF REGISTRATION

Brazilian Registry of Clinical Trials (RBR-4v6h7b) and date of registration April 4th, 2020.

Exercise-induced bronchospasm in obese adolescents

BACKGROUND

Assess the frequency and severity of exercise-induced bronchospasm (EIB) in obese adolescents.

METHODS

A cross-sectional descriptive study involving 80 adolescents of both genders, aged 10-16 years-old, divided into four groups according to clinical history of asthma and/or allergic rhinitis and body mass index as follows: asthmatic obese (n = 18); asthmatic non-obese (n = 21); obese non-asthmatic (n = 26); and healthy individuals (n = 15). An exercise bronchoprovocation test was used for EIB diagnosis, considered positive when the forced expiratory volume in one second (FEV(1)) decreased > or = 15% in relation to pre-exercise FEV(1). Maximum percent fall in FEV(1) (MF%FEV(1)) and area above the curve (AAC(0-30)) were calculated to evaluate EIB severity and recovery.

RESULTS

No significant difference was found in EIB frequency between asthmatic obese (50.0%) and asthmatic non-obese (38.0%) individuals or between obese non-asthmatics (11.5%) and healthy individuals (6.7%). However, the MF%FEV(1) and AAC(0-30) were significantly greater in the asthmatic obese group compared to the asthmatic non-obese (37.7% and 455 vs 24.5% and 214, p<0.03).

CONCLUSIONS

Obesity did not contribute to increased EIB frequency in asthmatics and non-asthmatics. However, obesity did contribute to increased EIB severity and recovery among asthmatics.

Nonequilibrium self-assembly of metals on diblock copolymer templates

Most studies of self-assembled systems reveal that the highest order is associated with equilibrium states of the system. By systematically studying metal decoration of diblock copolymer templates, I show that a high degree of order can arise under strongly nonequilibrium conditions. Under a wide range of conditions, thermally evaporated gold decorates ultrathin, asymmetric, polystyrene-b-polymethylmethacrylate diblock copolymer films with isolated nanoparticles. These particles aggregate into nanoparticle chains inside the polystyrene block with a selectivity approaching 100%. However, even at metal loading fractions of up to 30% by volume no coalescence into continuous nanowires is observed. This behavior is also shared by indium, tin, lead, bismuth, and silver at low coverage (<30 A nominal thickness). At high coverage (>100 A nominal thickness), however, silver self-assembles to form nanowires. One can understand the formation of the chains of nanoparticles by understanding the equilibrium state of the system (metal+polymer). The silver nanowires are highly nonequilibrium structures and, to the best of my knowledge, unexplained by existing theoretical models. Assuming an energy difference for metallic particles for either side of the diblock, a mobility difference, and an attractive interaction between metallic particles, I modeled the self-assembly of the nanowires with a Monte Carlo simulation. This Monte Carlo simulation qualitatively agrees with the formation of the silver nanowires and their relaxation to equilibrium upon moderate heating.

Hierarchical self-assembly of metal nanostructures on diblock copolymer scaffolds

Self-assembly is emerging as an elegant, 'bottom-up' method for fabricating nanostructured materials. This approach becomes particularly powerful when the ease and control offered by the self-assembly of organic components is combined with the electronic, magnetic or photonic properties of inorganic components. Here we demonstrate a versatile hierarchical approach for the assembly of organic-inorganic, copolymer-metal nanostructures in which one level of self-assembly guides the next. In a first step, ultrathin diblock copolymer films form a regular scaffold of highly anisotropic, stripe-like domains. During a second assembly step, differential wetting guides diffusing metal atoms to aggregate selectively along the scaffold, producing highly organized metal nanostructures. We find that, in contrast to the usual requirement of near-equilibrium conditions for ordering, the metal arranged on the copolymer scaffold produces the most highly ordered configurations when the system is far from equilibrium. We delineate two distinct assembly modes of the metal component-chains of separate nanoparticles and continuous wires-each characterized by different ordering kinetics and strikingly different current-voltage characteristics. These results therefore demonstrate the possibility of guided, large-scale assembly of laterally nanostructured systems.

Intensity autocorrelation measurements of an AlGaAs diode laser

We present measurements of the intensity autocorrelation function of the output of a free-running AlGaAs diode laser. To our knowledge these are the first such measurements performed on the output of a semiconductor laser. Our data display large structure at the relaxation oscillation frequency and reveal features that depend on the number of secondary modes lasing. This provides evidence that, even in so-called single-mode diode lasers, these side modes have a significant effect on the fluctuations of the total output of the laser. The autocorrelation function in fact can be used to measure how many modes contribute to the fluctuating intensity. The major features in the measured intensity autocorrelation function are in good agreement with the predictions of a simple multimode phase-diffusion model.