Screening for neurodegeneration in Langerhans cell histiocytosis with neurofilament light in plasma

Patients with Langerhans cell histiocytosis (LCH) may develop progressive neurodegeneration in the central nervous system (ND-CNS-LCH). Neurofilament light protein (NFL) in cerebrospinal fluid (CSF) is a promising biomarker to detect and monitor ND-CNS-LCH. We compared paired samples of NFL in plasma (p-NFL) and CSF in 10 patients (19 samples). Nine samples had abnormal CSF-NFL (defined as ≥380 ng/l) with corresponding p-NFL ≥ 2 ng/l. Ten samples had CSF-NFL < 380 ng/l; eight (80%) with p-NFL < 2 ng/l (p < 0.001; Fisher's exact test). Thus, our results suggest that p-NFL may be used to screen for ND-CNS-LCH. Further studies are encouraged, including the role of p-NFL for monitoring of ND-CNS-LCH

Human responses to cold and wind

Cold is stressful for the human being and has physical, subjective and physiological effects. Body cooling must be prevented to provide for the worker s comfort and safety in cold workplaces. The effects of cold were studied in view of the two predictive cold indices that are mainly used, IREQ (Insulation Required) for whole body cooling and WCI (Wind Chill Index) for bare skin cooling. The indices had scarcely been validated by physiological studies. WCI is mainly based on theoretical calculations and physical measurements. The influence of thermal state, light physical activity and wind speed on heat flows, temperature, cardiovascular and subjective responses and respiratory function were investigated at climate conditions calculated to be at the borderline of risk-no risk. Eight to ten young and middle-aged subjects participated in the studies. The subjects were dressed in multi-layer cold-protective clothing. They sat, stood or walked on a treadmill at 6 to 22 °C for 10-90 minutes in wind (1-6 m·s-1) and in the absence of wind. In one study the subjects were pre-cooled before the wind exposure. Even moderate wind speeds (2-6 m·s-1) at 10 °C caused the systolic and diastolic blood pressure to increase significantly, more at higher wind speed. They remained elevated without compensatory bradycardia. The air velocity also had effects on the skin temperatures. In about a fourth of the wind experiments the face temperature dropped to 0 °C. Pain was commonly reported at conditions below the risk level for frostbite in Wind Chill Index. The criteria of IREQ concerning body cooling were fulfilled, but hand temperatures were lower than recommended. In addition, finger temperatures were below 15 °C, which resulted in reduced manual performance. An increased exercise level was more effective to reheat fingers after cooling at 22 °C than adding insulation. At 10 °C moderate exercise reduced finger cooling more than low intensity exercise, but only at < 1 m·s-1. To be comfortable at low activity in cold it seems necessary to dress slightly more than indicated by IREQ and by thermal neutrality sensations. WCI seems to underestimate the cooling power of 5-6 m·s-1 at -10 °C of bare skin (e.g. face). The results provided suggestions for improving and developing IREQ and WCI. Prediction models for cold risk assessment should consider the large individual variation. The observations of blood pressure responses to cold wind exposure indicate that special attention should be taken at exposure to cold wind of physically inactive individuals, hypertensive persons and patients with heart disease.Kyla utgör en stressfaktor och har fysiologiska, subjektiva och fysikaliska effekter på människan. Nedkylning vid yrkesarbete måste förhindras för att komfort och säkerhet ska råda vid kallt arbete. Effekter av kyla studerades med avseende på de två vanligaste bedömningsmetoderna för kyla, IREQ (Insulation Required= isolationsbehov) för helkroppsavkylning och WCI (Wind Chill Index= vindkyleindex) för nedkylning av oskyddade kroppsdelar. Metoderna har inte validerats med fysiologiska studier i någon större omfattning. WCI baseras främst på teoretiska beräkningar och fysikaliska mätningar. Påverkan av fysisk aktivitet och vindhastighet på kropps- och hudtemperatur, på kardiovaskulära, respiratoriska och subjektiva reaktioner och värmebalans undersöktes under klimatbetingelser nära beräknade risknivåer. Åtta till tio unga och medelålders försökspersoner deltog, klädda i flera lager välisolerande kläder. De satt, stod och gick på ett rullband vid 6 °C till 22 °C i 10-90 minuter i vind (1-6 m·s-1) och i vindstilla (0.2 m·s-1). I en studie kyldes försökspersonerna innan de exponerades för kall vind. Även måttliga vindhastigheter (2-6 m·s-1) i 10 °C orsakade en signifikant ökning av det systoliska and diastoliska blodtrycket, som var större vid högre vindhastighet. Förhöjningen av blodtrycket kvarstod utan att kompenseras av en sänkning av hjärtfrekvensen. Lufthastigheten påverkade också hudtemperaturerna. I en fjärdedel av vindförsöken föll ansiktstemperaturen till 0 °C. Smärta upplevdes ofta i vind. Kriterierna för nedkylning av kroppen i IREQ uppfylldes, men handtemperaturerna var lägre än de rekommenderade. Dessutom var fingertemperaturerna under 15 °C, vilket resulterade i försämrad manuell förmåga. Ökning av arbetsintensiteten var effektivare för att värma upp fingrarna efter nedkylning i 22 °C än att öka klädernas isolation. I 10 °C minskade måttligt arbete nedkylningen av fingrarna mer än arbete vid lägre intensitet, men bara då vindhastigheten var < 1 m·s-1. För att känna sig behaglig vid låg fysisk aktivitet i kyla tycks det som om något mer isolation behövs än vad som rekommenderas i IREQ, även då termisk neutralitet upplevs. WCI tycks underskatta kyleffekten av 5-6 m·s-1 i -10 °C på bar hud (t ex. ansikte). Resultaten gav förslag för att förbättra och vidareutveckla IREQ och WCI. Bedömningsmetoder för fysiologiska risker i kyla bör ta hänsyn till den stora variationen mellan individer som observerades i kylaförsöken. De observerade blodtrycksreaktionerna vid exponering för kall vind kan innebära att försiktighetsåtgärder bör vidtas vid exponering för kyla och vind av personer som är fysiskt inaktiva, har förhöjt blodtryck eller hjärtsjukdom

Effectiveness of a light-weight ice-vest for body cooling while wearing fire fighter’s protective clothing in the heat

The aim of the study was to examine the effects of wearing an ice-vest (ca 1 kg) on physiological and subjective responses in fire fighters. The experiments were carried out on a treadmill in a hot-dry environment. The physical cooling effect of the ice-vest was measured with a thermal manikin. The ice-vest effectively reduced skin temperatures under the vest. On average, heart rate was 10 beats min-1 lower, amount of sweating was reduced by 13%, and subjective sensation of effort and warmth were lower during work with the ice-vest compared to work without it. Thermal manikin tests indicated, that the useful energy available from the vest for body cooling was rather high (58%). In conclusion, the ice-vest reduces physiological and subjective strain responses during heavy work in the heat, and may promote efficient work time by 10%

Correlations between aerobic capacity tests and field tests.

*<p>p<0.01. OBLA: Onset of blood lactate accumulation, LT: Lactate threshold. Percentage of maximal heart rate: % HR_max. Performance in the 3000 m running test is presented as absolute (s) and relative performance in relation to body-weight (s·kg⁻¹).VO_2max: maximal oxygen uptake<i>* p<0.01.</i></p

Anthropometrics and physical tests performance.

<p>Subject groups were: Male full-time firefighters (MFF), Male part-time firefighters (MPF), civilian men (CM), and civilian women (CW). Statistical Method (SM): Non-parametric tests (NP) are presented as medians ± Interquartile range (min-max), and parametric tests (P) are presented as means ± Standard deviation (min-max). One-Way ANOVA and Mann-Whitney (with Bonferroni correction) analysed subject group differences for P and NP variables, respectively. Only data for which there were significant differences among subject groups (p<0.01) are presented in the table, and marked with symbols in rows (*^{, †}). Groups denoted with different symbols are significantly different (*different from^†).</p><p>Investigated work tasks were: Carrying hose baskets up stairs (Stairs), Hose pulling (Pulling), Demolition at or after a fire (Demolition), Victim rescue (Rescue) and Carrying hose baskets over terrain (Terrain) Percentage use of maximal heart rate: % HR_max. Performance in the 3000 m running test is presented as relative performance (in relation to body-weight: s·kg⁻¹).</p>a<p><i>One CW subject did not begin the test.</i></p>b<p><i>One CW subject did not complete the test.</i></p

Schematic view of the work task course.

<p>The four work tasks: <i>carrying hose baskets in a staircase</i> (A), <i>hose pulling</i> (B), <i>demolition at or after a fire</i> (C) and <i>victim rescue</i> (D), was performed in sequence with two minutes of rest between each work task. The subject on the photograph has given written informed consent, as outlined in the PLOS consent form, to publication of their photograph.</p