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Biomedical subjects

M Camenzind

Publications and source records attributed to M Camenzind.

8 recordsLinked to original sources
PubMed2005

CO2 and O2 concentrations in integral motorcycle helmets.

Inhaling air which contains excess CO2 and/or is oxygen-deficient is known to present health risks and to diminish human cognitive abilities. The average CO2 concentrations relevant to a motorcyclist wearing an integral helmet were measured 20 years ago and found to be alarmingly large. The purpose of the present study was to examine gas concentrations typically inhaled by a motorcyclist. Average concentrations of CO2 near the upper lip for persons (n = 4) wearing integral motorcycle helmets were measured in the laboratory and the field to facilitate comparison to previous work, and similarly high average concentrations were found: above 2% when stationary, well below 1% for speeds of 50 km/h or more. Very good agreement was obtained between laboratory and field measurements. Detailed measurements of the time-dependent CO2 concentrations passing through a mouthpiece for mouth-breathing showed inhaled levels slightly over half of the corresponding average concentrations, including 1.3+/-0.3% at standstill, though higher concentrations (4% or more) were inhaled at the beginning of each breath. Opening the visor at standstill had on average no effect. At a speed of 50 km/h the inhaled CO2 concentration resembles that for a person without a helmet in still air, at about 0.2%. The oxygen deficiency is generally equal to the CO2 concentration, and could also contribute negatively to a motorcyclist's cognitive abilities.

Air Pollutants↗
PubMed2001

Determination of the ultraviolet protection factor of textile materials:measurement precision.

BACKGROUND: There is much interest in the use of textiles for sun protection. In vitro test methods are frequently used to assess the degree of protection to solar ultraviolet radiation of textile materials. It is, however, of paramount importance that methods are clearly described and that the precision of these methods is determined such that comparison between laboratories can be performed. An in vitro method for the determination of the Ultraviolet Protection Factor (UPF) is described in a new European Standard and is referred to as prEN 13758. Thirty experts from 11 European member states, forming a working group of the European Standardization Commission (CEN), have developed this method in consensus. In this paper the reliability of this test method for the determination of the UPF of textiles worn in close proximity to the skin and in a relaxed and dry state is studied. METHODS: For the determination of the precision of the test method, eight laboratories, using nine different measuring devices located in five different countries, have measured 14 textile materials of various types of construction and levels of UVR protection. Statistical analysis of the results has been performed according to ISO 5725. RESULTS: The repeatability standard deviation of the described method is independent of the UPF in the range 1-70 and is 1.36. The reproducibility standard deviation, however, clearly increases with the level of UPF. CONCLUSIONS: For high UPF values, differences between laboratories, due to factors such as different operators, equipment and calibration, can become important. This makes classification of high UPF materials questionable.

Humans↗
PubMed2000

Spatial variability of different fractions of particulate matter within an urban environment and between urban and rural sites.

The spatial variability of different fractions of particulate matter (PM) was investigated in the city of Basel, Switzerland, based on measurements performed throughout 1997 with a mobile monitoring station at six sites and permanently recorded measurements from a fixed site. Additionally, PM10 measurements from the following year, which were concurrently recorded at two urban and two rural sites, were compared. Generally, the spatial variability of PM4, PM10, and total suspended particulates (TSP) within this Swiss urban environment (area = 36 km2) was rather limited. With the exception of one site in a street canyon next to a traffic light, traffic density had only a weak tendency to increase the levels of PM. Mean PM10 concentration at six sites with different traffic densities was in the range of less than +/- 10% of the mean urban PM10 level. However, comparing the mean PM levels on workdays to that on weekends indicated that the impact of human activities, including traffic, on ambient PM levels may be considerable. Differences in the daily PM10 concentrations between urban and more elevated rural sites were strongly influenced by the stability of the atmosphere. In summer, when no persistent surface inversions exist, differences between urban and rural sites were rather small. It can therefore be concluded that spatial variability of annual mean PM concentration between urban and rural sites in the Basel area may more likely be caused by varying altitude than by distance to the city center.

Air Pollution↗
PubMed1987

Arotinoid ethyl ester (Ro 13-6298): a long term pilot study in various dermatoses.

The arotinoid ethyl ester Ro 13-6298 is a third generation retinoid shown to be thousand-fold more potent than etretinate (Tigason, Tegison) in animal testing and in human therapy. In an open uncontrolled trial, we treated 57 patients suffering from psoriasis (32) and various severe skin disorders (25) with daily doses ranging from 20 to 150 micrograms, during 1 to 130 weeks (mean = 12 weeks). Four patients were treated for 1 year or more. Given in micrograms per kg range, Ro 13-6298 showed a spectrum of clinical activity and mucocutaneous side effects similar to that of etretinate given in mg per kg range. One patient developed diffuse idiopathic skeletal hyperostosis after 2 years of continuous therapy. No increase in either serum triglycerides or cholesterol levels was observed, even in patients treated for 33 to 130 weeks. This might prove to be an advantage of this new retinoid. Furthermore, this series suggests that potent mucocutaneous (therapeutical and side) effects are not necessarily linked to all other signs of retinoid toxicity.

Adult↗
PubMed1986

Cellular retinoic acid- but not cellular retinol-binding protein is elevated in psoriatic plaques.

Cellular retinoid binding proteins are thought to be involved in the molecular action of retinoids, a family of compounds successfully used in the treatment of psoriasis. Therefore, both cellular retinol (CRBP)- and retinoic acid (CRABP)-binding proteins were analyzed in psoriatic skin. Three facts emerged from our study: both CRABP and CRBP are detectable in the skin of psoriatic patients; qualitatively, they both appear similar to the corresponding proteins of normal human skin, in terms of their elution profile and apparent Kd; and quantitatively, only CRABP was found to be 3 times higher in psoriatic plaques as compared to either nonlesional skin of psoriatic patients or the skin of normal subjects. Since psoriatic plaques are particularly responsive to systemic retinoids, specifically to retinoic acid analogues, our results suggest for the first time a link between the levels of CRABP and the responsiveness of a nonneoplastic hyperproliferative tissue to systemic administration of retinoids in the human.

Adult↗