Comparison of air-displacement plethysmography and hydrodensitometry in high school football linemen

Recently, there has been concern about obesity and its co-morbidities among football linemen from the youth to professional level. The purpose of this study was two-fold: (1) to examine the association between body mass index (BMI) and percentage fat determined by air-displacement plethysmography (ADP) and hydrodensitometry (HW) in high school football linemen and (2) to compare ADP with HW in high school football linemen to determine the feasibility and accuracy of ADP compared with HW in this group. Thirty-one high school football linemen were recruited from local high schools and were measured for height, body mass, and percentage fat estimated from ADP and HW. BMI (kg/m 2) was calculated from the measured height and body mass.;A majority of subjects were at-risk of being overweight (32%) or overweight (55%), and 6.5% had BMI ≥ 35 kg/m2. The mean percentage fat approximated 20% for both ADP and HW measures. BMI was significantly correlated with percentage body fat for ADP (r=0.68) and HW (r=0.76). BMI was significantly correlated with fat mass (FM) and fat-free mass (FFM) for both ADP (FM r=0.83, FFM r=0.49) and HW (FM r=0.88, FFM r=0.57). When analyzed by weight status (non-overweight or overweight), HW was significantly correlated with BMI for the non-overweight group (r=0.72) and overweight group (r=0.54). FM was significantly correlated with BMI for both ADP and HW, respectively, in the nonoverweight (r=0.60 and r=0.75) and overweight (r=0.64 and r=0.78) groups. Significant correlations were also noted between FFM and BMI for both ADP (r=0.68) and HW (r=0.56) but only in the overweight group. Percentage fat based upon ADP and HW were significantly correlated (r=0.68) and the mean difference between HW and ADP was -1.4%. Group analysis revealed a significant correlation in body fat percentage between ADP and HW (r=0.78) only in the non-overweight group. BMI showed a high sensitivity (1.0) for identifying subjects with high body fat as overweight and a moderately high specificity (0.6-0.7) for identifying subjects with lower body fat as normal weight, i.e. suggesting some tendency to misclassify subjects with lower body fat as overweight.;In conclusion, although the BMI correlated reasonably well with fatness in this group and can be used as a first step in the screening process for overweight and obesity, caution should be used due to the tendency that individuals with lower body fat values may be misclassified as overweight about half the time. These two methods of body composition analysis showed that ADP tended to overestimate percentage body fat by ∼1.4% compared to HW; however, there was considerable variation in the error among the sample. Furthermore, ADP showed a slightly greater tendency to overestimate body fat percentage as the body size of subjects increased. Although there are several limitations to both procedures, the advantage of ADP in this group was its greater ease of measurement and acceptability compared with HW

Neutral lipids associated with haemozoin mediate efficient and rapid beta-haematin formation at physiological pH, temperature and ionic composition

BACKGROUND: The malaria parasite disposes of host-derived ferrihaem (iron(III)protoporphyrin IX, Fe(III)PPIX) by conversion to crystalline haemozoin in close association with neutral lipids. Lipids mediate synthetic haemozoin (beta-haematin) formation very efficiently. However, the effect on reaction rates of concentrations of lipid, Fe(III)PPIX and physiologically relevant ions and biomolecules are unknown. METHODS: Lipid emulsions containing Fe(III)PPIX were prepared in aqueous medium (pH 4.8, 37degreesC) to mediate beta-haematin formation. The reaction was quenched at various times and free Fe(III)PPIX measured colorimetrically as a pyridine complex and the kinetics and yields analysed. Products were also characterized by FTIR, TEM and electron diffraction. Autofluorescence was also used to monitor beta-haematin formation by confocal microscopy. RESULTS: At fixed Fe(III)PPIX concentration, beta-haematin yields remained constant with decreasing lipid concentration until a cut-off ratio was reached whereupon efficiency decreased dramatically. For the haemozoin-associated neutral lipid blend (NLB) and monopalmitoylglycerol (MPG), this occurred below a lipid/Fe(III)PPIX (L/H) ratio of 0.54. Rate constants were found to increase with L/H ratio above the cut-off. At 16 muM MPG, Fe(III)PPIX concentration could be raised until the L/H ratio reached the same ratio before a sudden decline in yield was observed. MPG-mediated beta-haematin formation was relatively insensitive to biologically relevant cations (Na+, K+, Mg2+, Ca2+), or anions (H2PO4, HCO3, ATP, 2,3-diphosphoglycerate, glutathione). Confocal microscopy demonstrated beta-haematin formation occurs in association with the lipid particles. CONCLUSIONS: Kinetics of beta-haematin formation have shown that haemozoin-associated neutral lipids alone are capable of mediating beta-haematin formation at adequate rates under physiologically realistic conditions of ion concentrations to account for haemozoin formation

Rétroaction multisources à la suite d’une simulation en réanimation : une étude qualitative

Background: The direct observation and assessment of learners’ resuscitation skills by an attending physician is challenging due to the unpredictable and time-sensitive nature of these events. Multisource feedback (MSF) may address this challenge and improve the quality of assessments provided to learners. We aimed to describe the similarities and differences in the assessment rationale of attending physicians, registered nurses, and resident peers in the context of a simulation-based resuscitation curriculum. Methods: We conducted a qualitative content analysis of narrative MSF of medical residents in their first postgraduate year of training who were participating in a simulation-based resuscitation course at two Canadian institutions. Assessments included an entrustment score and narrative comments from attending physicians, registered nurses, and resident peers in addition to self-assessment. Narrative comments were transcribed and analyzed thematically using a constant comparative method. Results: All 87 residents (100%) participating in the 2017-2018 course provided consent. A total of 223 assessments were included in our analysis. Four themes emerged from the narrative data: 1) Communication, 2) Leadership, 3) Demeanor, and 4) Medical Expert. Relative to other assessor groups, feedback from nurses focused on patient-centred care and communication while attending physicians focused on the medical expert theme. Peer feedback was the most positive. Self-assessments included comments within each of the four themes. Conclusions: In the context of a simulation-based resuscitation curriculum, MSF provided learners with different perspectives in their narrative assessment rationale and may offer a more holistic assessment of resuscitation skills within a competency-based medical education (CBME) program of assessment.Contexte : Le contexte imprévisible et contraignant au niveau du temps lors de l’observation directe et de la rétroaction associée sur les compétences en réanimation des apprenants constituent un défi pour un médecin superviseur. La rétroaction multisources (RMS) peut être un moyen de relever ce défi et d'améliorer la qualité des rétroactions fournies aux apprenants. Nous visons à décrire les similitudes et les différences quant à la démarche évaluative auprès de médecins traitants, d’infirmières cliniciennes et de pairs résidents dans le cadre d'un cours de réanimation offert par simulation. Méthodes : Nous avons réalisé une analyse de contenu à partir des rétroactions narratives offertes aux résidents en première année de formation postdoctorale dans deux universités canadiennes dans le cadre d’un cours de réanimation offert par simulation. En plus de l’auto-évaluation, la rétroaction comportait un score de confiance et des commentaires narratifs de la part de médecins superviseurs, d’infirmières cliniciennes et des pairs. Les commentaires ont été transcrits et analysés par thèmes en appliquant la méthode générale de comparaison constante. Résultats : Un consentement pour participer à l’étude a été obtenu auprès des 87 résidents (100 %) qui ont suivi le cours en 2017-2018. Nous avons analysé un total de 223 rétroactions. Quatre thèmes ont émergé à partir des données narratives soit : 1) la communication, 2) le leadership, 3) le comportement, et 4) l’expertise médicale. Alors que les infirmières ont ciblé leurs commentaires sur les soins centrés sur le patient et la communication, les médecins superviseurs ont les ont ciblés sur l’expertise médicale. Les commentaires des pairs étaient les plus positifs. Les auto-évaluations comportaient des commentaires sur chacun des quatre thèmes. Conclusions : Dans le contexte d’un cours de réanimation offert par simulation, la RMS a permis aux apprenants d’obtenir des évaluations narratives selon différentes perspectives. Permettant ainsi une approche plus holistique de rétroaction sur les habiletés en réanimation dans le cadre d’un programme d’évaluation axé sur les compétences

A concept for seeing-limited near-IR spectroscopy on the Giant Magellan Telescope

We present a simple seeing-limited IR spectrometer design for the Giant Magellan Telescope, with continuous R = 6000 coverage from 0.87-2.50 microns for a 0:7” slit. The instrument's design is based on an asymmetric white pupil echelle layout, with dichroics splitting the optical train into yJ, H, and K channels after the pupil transfer mirror. A separate low-dispersion mode offers single-object R ~ 850 spectra which also cover the full NIR bandpass in each exposure. Catalog gratings and H2RG detectors are used to minimize cost, and only two cryogenic rotary mechanisms are employed, reducing mechanical complexity. The instrument dewar occupies an envelope of 1:8×1:5×1:2 meters, satisfying mass and volume requirements for GMT with comfortable margin. We estimate the system throughput at ~ 35% including losses from the atmosphere, telescope, and instrument (i.e. all coatings, gratings, and sensors). This optical efficiency is comparable to the FIRE spectrograph on Magellan, and we have specified and designed fast cameras so the GMT instrument will have an almost identical pixel scale as FIRE. On the 6.5 meter Magellan telescopes, FIRE is read-noise limited in the y and J bands, similar to other existing near-IR spectrometers and also to JWST/NIRSPEC. GMT's twelve-fold increase in collecting area will therefore offer gains in signal-to-noise per exposure that exceed those of moderate resolution optical instruments, which are already sky-noise limited on today's telescopes. Such an instrument would allow GMT to pursue key early science programs on the Epoch of Reionization, galaxy formation, transient astronomy, and obscured star formation environments prior to commissioning of its adaptive optics system. This design study demonstrates the feasibility of developing relatively affordable spectrometers at the ELT scale, in response to the pressures of joint funding for these telescopes and their associated instrument suites.Massachusetts Institute of Technology. Department of Physics.Kavli Institute for Astrophysics and Space Researc

Kinetics of b-haematin formation from suspensions of haematin in aqueous benzoic acid

Kinetics of b-haematin (synthetic malaria pigment) formation from haematin have been studied in the presence of aqueous benzoic acid and derivatives of benzoic acid. Formation of the b-haematin product is demonstrated by X-ray diffraction and IR spectroscopy. Reactions were followed by determining the fraction of unreacted haematin at various time points during the process via reaction of extracted aliquots with pyridine. The kinetics can be fitted to the Avrami equation, indicating that the process involves nucleation and growth. Reaction kinetics in stirred benzoic acid are similar to those previously observed in acetic acid, except that benzoic acid is far more active in promoting the reaction than acetic acid. The reaction reaches completion within 2 h in the presence of 0.050 M benzoic acid (pH 4.5, 60 • C). This compares with 1 h in the presence of 4.5 M acetic acid and 4 h in the presence of 2 M acetic acid. The reaction rate in benzoic acid is not affected if the stirring rate is decreased to zero, but very vigorous stirring appears to disrupt nucleation. The rate constant for b-haematin formation in benzoic acid has a linear dependence on benzoic acid concentration and follows Arrhenius behaviour with temperature. There is a bell-shaped dependence on pH. This suggests that the haematin species in which one propionate group is protonated and the other is deprotonated is optimal for b-haematin formation. When the reaction is conducted in para-substituted benzoic acid derivatives, the log of the rate constant increases linearly with the Hammett constant. These findings suggest that the role of the carboxylic acid may be to disrupt hydrogen bonding and p-stacking in haematin, facilitating conversion to b-haematin. The large activation energy for conversion of precipitated haematin to b-haematin suggests that the reaction in vivo most likely involves direct nucleation from solution and probably does not occur in aqueous medium

Increase on the Initial Soluble Heme Levels in Acidic Conditions Is an Important Mechanism for Spontaneous Heme Crystallization In Vitro

BACKGROUND: Hemozoin (Hz) is a heme crystal that represents a vital pathway for heme disposal in several blood-feeding organisms. Recent evidence demonstrated that β-hematin (βH) (the synthetic counterpart of Hz) formation occurs under physiological conditions near synthetic or biological hydrophilic-hydrophobic interfaces. This seems to require a heme dimer acting as a precursor of Hz crystals that would be formed spontaneously in the absence of the competing water molecules bound to the heme iron. Here, we aimed to investigate the role of medium polarity on spontaneous βH formation in vitro. METHODOLOGY/PRINCIPAL FINDINGS: We assessed the effect of water content on spontaneous βH formation by using the aprotic solvent dimethylsulfoxide (DMSO) and a series of polyethyleneglycols (PEGs). We observed that both DMSO and PEGs (3.350, 6.000, 8.000, and 22.000) increased the levels of soluble heme under acidic conditions. These compounds were able to stimulate the production of βH crystals in the absence of any biological sample. Interestingly, the effects of DMSO and PEGs on βH formation were positively correlated with their capacity to promote previous heme solubilization in acidic conditions. Curiously, a short chain polyethyleneglycol (PEG 300) caused a significant reduction in both soluble heme levels and βH formation. Finally, both heme solubilization and βH formation strongly correlated with reduced medium water activity provided by increased DMSO concentrations. CONCLUSIONS: The data presented here support the notion that reduction of the water activity is an important mechanism to support spontaneous heme crystallization, which depends on the previous increase of soluble heme levels

An eHealth Android Application for Mobile Analysis of Microplate Assays

Drug efficacy assays with microplate readers are a key aspect of the modern drug discovery process. However, microtitre plate readers are expensive laboratory equipment and not easily transportable. We have created a prototype Android smartphone application that enables smartphones to measure the concentration values in microplate wells. We find that the smartphone camera measures concentrations of red and yellow solutions more accurately than green. Further, concentration readings are most accurate when microplates are backlit and sources of noise (such as glare and shadows) are removed. Therefore, we designed a simple dark box to control ambient light, which reduces the error in measurements to within 7% of a laboratory microplate reader. An affordable and mobile alternative to a microplate reader is expected to support drug research in developing countries by enabling rapid, cheap drug assays in small laboratories and in field work with a standard Android smartphone