Metabolic Energy Requirements during Load Carriage: Implications for the Wildland Firefighter Arduous Pack Test

Despite extensive and ongoing scientific study into the metabolic requirements of load carriage, an understanding quantifying the effect of speed, load, sex and body mass has yet to come forth and the extent to which established models predict these requirements is largely untested. Specifically, because existing experimental efforts have typically focused on relatively modest walking speeds using loads representing a fixed portion of the subject’s mass, extending the available predictions to applications where individuals complete a common task carrying an identical absolute load provides estimates of unknown accuracy. PURPOSE: Here, we measured the energy use in a large subject group walking at speeds surrounding the 1.8 m s-1 necessary to successfully complete the 4.83 km USFS wildland firefighter arduous pack (20.5kg) test, and compared these results to estimates available from the prevailing models. METHODS: We measured VO2 from 61 young (age = 22.8±3.2 yrs) adults (36 males; 25 females; study range: Mb = 55.4-119.6 kg; height = 1.52-1.93 m) as they performed four, 5min trials, with a 20.5kg pack, on a level treadmill at 1.7, 1.8, 1.9 m s-1, and their individual average speed from a previously administered pack test. In addition, a subset of n=10 subjects were equipped with Douglas bags during the simulated pack test to measure steady state VO2. We used the methods of Pandolf et al. 1977 and Ludlow & Weyand 2017 to generate VO2 estimates for the individual trials we administered. RESULTS: Measured values of VO2 increased from 22.4±3.2 and 24.6±4.1 ml kg-1 min-1 at 1.7 m s-1,to 31.6±5.3 and 31.0±4.5 ml kg-1 min-1 at the fastest speed administered for males and females respectively. In contrast, the accuracy of the predictive models decreased with speed and yielded prediction errors of -12.4 and -22.9% at 1.7 m s-1 for the Pandolf and Ludlow & Weyand methods respectively, these errors were -18.0 and -32.2% at the fastest speeds administered. When evaluated at the speed subjects used in the field trial, the prediction models underestimated energy expenditure by 5.0±4.4 and 10.4±4.9 mlO2·kg-1·min-1 respectively. CONCLUSION: We conclude that existing predictive models do not retain their accuracy, and substantially underestimate measured values when applied to a group of male and female subjects undertaking relatively fast walking speeds on a flat surface with a heavy load

Sex-related differences in cerebrospinal fluid plasma-derived proteins of neurological patients

none11Background and aims: Cerebrospinal fluid (CSF) protein content presents a sexual dimor- phism in humans. We investigated sex-related differences in CSF IgG levels and in the quantification of intrathecal IgG synthesis (IIS). Methods: CSF, serum albumin and IgG were measured in 1519 neurological patients and both linear and hyperbolic formulas were used for the quantification of IIS. CSF-restricted oligoclonal IgG bands (OCBs) were used as “gold standard”. Results: The linear IgG Index showed a weak agreement with OCBs in males and females (k = 0.559, k = 0.587, respectively), while the hyperbolic Reiber’s formulas had a moderate agreement with OCBs in females (k = 0.635) and a weak agreement in males (k = 0.565). Higher CSF albumin and IgG levels were found in men than in women in the whole population and in subjects without IIS after adjusting for age and for serum concentrations of albumin and IgG, respectively (Quade statistics, p < 0.000001). CSF and serum albumin and IgG levels positively correlated to age in both sexes. CSF total protein content did not correlate with CSF leukocyte numbers but was higher in patients with marked pleocytosis. Conclusions: In neurological patients, men have higher levels of CSF serum-derived proteins, such as albumin and IgG.openCastellazzi, Massimiliano; Ferri, Caterina; Alfiero, Sarah; Lombardo, Ilenia; Laudisi, Michele; Tecilla, Ginevra; Boni, Michela; Pizzicotti, Stefano; Fainardi, Enrico; Bellini, Tiziana; Pugliatti, MauraCastellazzi, Massimiliano; Ferri, Caterina; Alfiero, Sarah; Lombardo, Ilenia; Laudisi, Michele; Tecilla, Ginevra; Boni, Michela; Pizzicotti, Stefano; Fainardi, Enrico; Bellini, Tiziana; Pugliatti, Maur

Lower grade gliomas: relationships between metabolic and structural imaging with grading and molecular factors

Background: Positron emission tomography (PET) is a valuable tool for the characterization of brain tumors in vivo. However, few studies have investigated the correlation between carbon-11-methionine (11C-METH) PET metrics and the clinical, radiological, histological, and molecular features of patients affected by lower grade gliomas (LGGs). The present observational study evaluated the relationships between 11C-METH PET metrics and structural magnetic resonance imaging (MRI) findings with the histomolecular biomarkers in patients with LGGs who were candidates for surgery. Methods: We enrolled 96 patients with pathologically proven LGG (51 men, 45 women; age 44.1 \ub1 13.7 years; 45 with grade II, 51 with grade III), who had been referred from March 2012 to January 2015 for tumor resection and had undergone preoperative 11C-METH PET. The semiquantitative metrics for 11C-METH PET included maximum standardized uptake value (SUVmax), SUV ratio to normal brain, and metabolic tumor burden (MTB). The PET semiquantitative metrics were analyzed and compared with the MRI features, histological diagnosis, isocitrate dehydrogenase-1/2 status, and 1p/19q codeletion. Results: Histological grade was associated with SUVmax (P = 0.002), SUV ratio (P = 0.011), and MTB (P = 0.001), with grade III lesions showing higher values. Among the nonenhancing lesions on MRI, SUVmax (P = 0.001), SUV ratio (P = 0.003) and MTB (P < 0.001) were significantly different statistically for grade II versus grade III. The MRI lesion volume correlated poorly with MTB (r 2 = 0.13). The SUVmax and SUV ratio were greater (P < 0.05) in isocitrate dehydrogenase-1/2 wild-type lesions, and the SUV ratio was associated with the presence of the 1p19q codeletion. Conclusions: The 11C-METH PET metrics correlated significantly with histological grade and the molecular profile. Semiquantitative PET metrics can improve the preoperative evaluation of LGGs and thus support clinical decision-making

Quantifying the organization of urban elements through the statistical distributions of their spatial spreading metrics

We probe the underlying organization emerging out of the growth of urban settlements by using various measures that quantify their spatial spreading. In particular, we report the emergence of fat-tailed regimes in the distributions of the three metrics we investigated in the case of the self-organized Metro Manila conurbation: (1) the city road lengths and the areas of road-bounded blocks; (2) the Voronoi areas, the effective “areas of influence” of each of the buildings in the city; and (3) the k role= presentation style= box-sizing: border-box; margin: 0px; padding: 0px; display: inline-block; line-height: normal; font-size: 16.2px; word-spacing: normal; overflow-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; position: relative; \u3ek-nearest-neighbor (kNN) distances of economic structures in the city. Statistical goodness-of-fit tests are conducted to obtain representative decaying power-law trends for these fat-tailed distributions, as a first approximation for the scaling behavior, particularly at the largest scales. The obtained distributions are found to differ significantly from the corresponding results generated from memoryless null models. The key insights from these data analyses add to the growing literature on quantitative characterizations of urban zones, and may help uncover the underlying mechanics responsible for growth