Measurement of 24-h continuous human CH4 release in a whole room indirect calorimeter.

We describe the technology and validation of a new whole room indirect calorimeter (WRIC) methodology to quantify volume of methane (VCH4) released from the human body over 24 h concurrently with the assessment of energy expenditure and substrate utilization. The new system extends the assessment of energy metabolism by adding CH4, a downstream product of microbiome fermentation that could contribute to energy balance. Our new system consists of an established WRIC combined with the addition of off-axis integrated-cavity output spectroscopy (OA-ICOS) to measure CH4 concentration ([CH4]). Development, validation, and reliability of the system included environmental experiments to measure the stability of the atmospheric [CH4], infusing CH4 into the WRIC and human cross-validation studies comparing [CH4] quantified by OA-ICOS and mid-infrared dual-comb spectroscopy (MIR DCS).Our infusion data indicated that the system measured 24-h [CH4] and VCH4 with high sensitivity, reliability, and validity. Cross-validation studies showed good agreement between OA-ICOS and MIR DCS technologies (r = 0.979, P < 0.0001). Human data revealed 24-h VCH4 was highly variable between subjects and within/between days. Finally, our method to quantify VCH4 released by breath or colon suggested that over 50% of the CH4 was eliminated through the breath. The method allows, for the first time, measurement of 24-h VCH4 (in kcal) and therefore the measurement of the proportion of human energy intake fermented to CH4 by the gut microbiome and released via breath or from the intestine; also, it allows us to track the effects of dietary, probiotic, bacterial, and fecal microbiota transplantation on VCH4.NEW & NOTEWORTHY This is the first time that continuous assessment of CH4 is reported in parallel with measurements of O2 consumption and CO2 production inside a whole room indirect calorimeter in humans and over 24 h. We provide a detailed description of the whole system and its parts. We carried out studies of reliability and validity of the whole system and its parts. CH4 is released in humans during daily activities.

Is physical education an effective way to increase physical activity in children with lower cardiorespiratory fitness?

Several findings revealed the importance of accruing moderate and vigorous physical activity (MVPA) to improve health. Physical education (PE) may play an important role on promoting children's MVPA. However, it remains unknown whether PE might be effective when increasing physical activity (PA) levels in children with lower cardiorespiratory fitness (CRF). Therefore, the aim of this study was to assess children's PA during PE and during days with and without PE with a special focus on CRF status. One hundred and fifty Spanish children and adolescents from 3rd to 12th grade were recruited. PA levels were assessed with GT3X accelerometers. Peak oxygen uptake (VO2peak ) was estimated using a portable breath by breath Metamax 3B. Participants were classified as healthy aerobic fitness (HAF) and unhealthy aerobic fitness (UHAF) according to standardized cut-off point criteria. During PE, students with HAF accrued more MVPA than those with UHAF (8.7 vs 5.7 min/session; P ≤ 0.001). MVPA was higher on PE days than days without for both UHAF (50.0 vs 42.7 min/day; P ≤ 0.05) and HAF students (56.9 vs 49.4 min/day; P ≤ 0.05). Although less active during PE, students with lower CRF accumulated more MVPA and total PA on PE days than days without PE. An increase in PE days might be a smart policy to raise the recommended PA levels, regardless of CRF status.

Weekly training hours are associated with molecular and cellular body composition levels in adolescent athletes.

AIM: We aimed to explore associations between hours per week of sports training and molecular and cellular body composition components in adolescent athletes. METHODS: A total of 33 female athletes (13.3+/-3.5 years; 47.8+/-12.6 kg; 154+/-14.0 cm) and 90 male athletes (14.1+/-2.7 years; 60.6+/-17.8 kg; 167+/-16.2 cm) were measured. Based on the total of hours per week of training, athletes were divided into tertiles: <4.5 h/week; 4.5-8.9 h/week; 9 h/week. Dual-energy X-ray absorptiometry (DXA) was used to assess lean mass (lean), body fat (BF), percent body fat (%BF), bone mineral content (BMC) and density (BMD). Total body water (TBW), intracellular (ICW) and extracellular water (ECW) were assessed using bioelectrical impedance spectroscopy (BIS). Extracellular fluids (ECF), solids (ECS), body cell mass (BCM) and body fluid distribution (E/I) were calculated. Total hours per week of sports training (h/week), habitual physical activity (PA) and dietary were assessed by questionnaire. Statistics included analysis of covariance (ANCOVA) and simple regression analyses. RESULTS: Athletes training 9 h/week presented greater levels of TBW, lean, bone mass, BCM, and ECF and a lower %BF, independently of confounders. No significant differences in body composition estimates were found between athletes training <9 h/week. Hours per week of sports training were positively associated with fat free components, only in the group exercising 9 h/week CONCLUSIONS: In this group of Portuguese athletes from different sports we observed that training 9 h/week significantly improved body composition, especially fat free components, which may be important for a healthy growth and sports performance.

Body surface area estimation and its impact on predicting appendicular skeletal muscle mass with a mechanistic model based on the Reference Man.

The purpose of this study was to analyze the difference between the equations presented by Du Bois and Du Bois (1916) and Livingston and Lee (2001), used to estimate body surface area (BSA) and its impact on predicting appendicular skeletal muscle mass (ASMM) in adults, using a model based on the Reference Man (Fuller et al. 1992). Subjects were 666 Caucasian women (44.3+/-15.2 years, 63.7+/-10.5 kg, 1.57+/-0.07 m, 26.0+/-4.3 kg/m(2)) and 316 Caucasian men (42.8+/-15.4 years, 79.8+/-12.5 kg, 1.72+/-0.07 m, 26.8+/-3.8 kg/m(2)). Dual-energy X-ray absorptiometry was used to assess fat mass and fat-free mass. Du Bois's and Livingston's BSA equations were used to calculate ASMM according to Fuller's method. As compared to the new Livingston equation, Du Bois's equation underestimated ( p<0.05) BSA in women (-0.08 m(2)) and in men (-0.06 m(2)). On the other hand, ASMM was overestimated in the arms, legs, and total body with Du Bois's equation. This effect was of greater magnitude in obese subjects.

Relationship between absorptiometry and ultrasound measurements of abdominal subcutaneous fat tissue in postmenopausal women.

The purpose of this study was to describe the association of abdominal subcutaneous adipose tissue (SAT) as assessed by ultrasound with fat tissue in the abdomen, trunk, and other areas as measured by DXA in 101 postmenopausal Caucasian women (62.5 years; 27.3 kg/m(2); 43.0% body fat). Ultrasound SAT thickness was calculated with electronic calipers positioned at the skin-fat and fat-muscle computer screen interface, at the suprailiac (SUPT) and abdominal (ABDT) sites. Pearson correlation showed significant ( p<0.001) coefficients between SAT by DXA at both ABDT ( r=0.644) and SUPT ( r=0.537). Other DXA measurements were also associated ( p<0.001) with SAT assessed by DXA and ultrasound. In postmenopausal women, DXA estimates of subcutaneous and total adiposity are moderately associated with ultrasound measures of fat in the abdomen. Future research at our and other laboratories should clarify the clinical and practical significance of these findings.

bgs2+, a sporulation-specific glucan synthase homologue is required for proper ascospore wall maturation in fission yeast.

The formation of the ascospore cell wall of Schizosaccharomyces pombe requires the co-ordinated activity of enzymes involved in the biosynthesis of its components, such as glucans. We have cloned the bgs2+ gene. bgs2+ belongs to the glucan synthase family of S. pombe and is homologous to the Saccharomyces cerevisiae FKS1 and FKS2 genes. Deletion or overexpression of this gene does not lead to any apparent defect during vegetative growth, but homozygous bgs2Delta diploids do show a sporulation defect. Although meiosis takes place normally, ascospores are unable to mature, and their wall differs from that of wild-type ascospores. Moreover, bgs2Delta zygotes were not able to release ascospores spontaneously, and the ascospores were unable to germinate. We show that expression of bgs2+ is restricted to sporulation and that a bgs2-green fluorescent protein (GFP) fusion protein localizes to the ascospore envelope. The glucan synthase activity in sporulating diploids bearing a bgs2 deletion was diminished in comparison with that of the wild-type diploids, a fact that underscores the importance of the bgs2+ gene and glucan synthesis for the proper formation and maturation of the ascospore wall.

Schizosaccharomyces pombe ehs1p is involved in maintaining cell wall integrity and in calcium uptake.

The Schizosaccharomyces pombe mutant ehs1-1 mutant was isolated on the basis of its hypersensitivity to Echinocandin and Calcofluor White, which inhibit cell wall synthesis. The mutant shows a thermosensitive growth phenotype that is suppressed in the presence of an osmotic stabiliser. The mutant also showed other cell wall-associated phenotypes, such as enhanced sensitivity to enzymatic cell wall degradation and an imbalance in polysaccharide synthesis. The ehs1 + gene encodes a predicted integral membrane protein that is 30% identical to Saccharomyces cerevisiae Mid1p, a protein that has been proposed to form part of a calcium channel. As expected for such a function, we found that ehs1+ is involved in intracellular Ca2+ accumulation. High external Ca2+ concentrations suppressed all phenotypes associated with the ehs1 null mutation, suggesting that the cell integrity defects of ehs1 mutants result from inadequate levels of calcium in the cell. We observed a genetic relationship between ehs1+ and the protein kinase C homologue pck2+. pck2+ suppressed all phenotypes of ehs1-1 mutant cells. Overproduction of pck2p is deleterious to wild-type cells, increasing 1,3-beta-D-glucan synthase activity and promoting accumulation of extremely high levels of Ca2+. The lethality associated with pck2p, the increase in 1,3-beta-D-glucan synthase production and the strong Ca2+ accumulation are all dependent on the presence of ehs1p. Our results suggest that in fission yeast ehs1p forms part of a calcium channel that is involved in the cell wall integrity pathway that includes the kinase pck2p.

Influenza virus NS1 protein counteracts PKR-mediated inhibition of replication.

The availability of an influenza virus NS1 gene knockout virus (delNS1 virus) allowed us to establish the significance of the biological relationship between the influenza virus NS1 protein and double-stranded-RNA-activated protein kinase (PKR) in the life cycle and pathogenicity of influenza virus. Our results show that the lack of functional PKR permits the delNS1 virus to replicate in otherwise nonpermissive hosts, suggesting that the major function of the influenza virus NS1 protein is to counteract or prevent the PKR-mediated antiviral response.