Novel approach for assessing performance of PCR cyclers used for diagnostic testing.

As part of a large international project for validation and standardization of PCR, the influence of thermocyclers on PCR was tested. Six brand-new, Peltier technology-driven 96-well thermocyclers were subjected to a novel and stringent in-tube (not block) physical testing. The temperature was directly monitored in PCR tubes containing 50 microl of distilled water at 13 different block positions. The certified temperature accuracy of the measurement system was +/-0.3 degrees C. Finally, the results of the physical testing were compared to those of an amplification efficiency study running an in-house PCR assay. The cyclers did not perform within the manufacturer's specification. Premature timing, under- and overshooting, and spatial variation of heat transfer were found to be the critical factors. The physical testing allowed us to distinguish accurate from less-accurate (2/6) cyclers. The lack of thermal homogeneities became most evident at the denaturation level during the first 15 s. At the time point zero, the accurate cyclers showed temperature deviations of 0.5 to 1.5 degrees C, whereas less-accurate cyclers failed to reach the set temperature by 13 to 20 degrees C. Consequently, the two less-accurate cyclers could not gain positive PCR results by running an in-house PCR assay. However, by modifying the original temperature protocol by increasing the denaturation temperature and time, the amplification efficiency of these two cyclers could be improved significantly. The results have implication for laboratories using diagnostic PCR testing.

Ultraviolet protective performance of photoprotective lipsticks: change of spectral transmittance because of ultraviolet exposure.

BACKGROUND: Photoinstability of sunscreens because of ultraviolet (UV) exposure is a well-known and common phenomenon. Recently, it was also shown that sunscreens with complex filter combinations are photoinactivated by UV exposures, which can easily be acquired by solar exposure over several hours. OBJECTIVES: To assess the change of the spectral transmission after UV exposure (UV-challenged protective performance) of 27 commercially available photoprotective lipsticks. METHODS: Quartz slides were covered with a lipstick layer (area density 1.0+/-0.1 mg/cm2) and irradiated with increasing doses of solar-simulated radiation. The spectral transmission (T) was measured spectrophotometrically before and after 5, 12.5, 25, and 50 standard erythema doses (SED) of exposure. We calculated the change in transmission (photoinstability) as the difference between the spectral transmission before and after a defined UV exposure, DeltaT, and the arithmetic mean, for both the UVA (DeltaTA) and UVB (DeltaTB) ranges. A product was labelled as photounstable if the mean photoinstability in the UVA, DeltaTA, or UVB range, DeltaTB, was higher than 5% for an UV exposure of 12.5 SED. RESULTS: Eleven products showed a significant photoinstability in the UVA range (DeltaTA between 6% and 27%), only one product in the UVB range (DeltaTB = 13%), and one product in both the UVA (DeltaTA = 31%) and UVB (DeltaTB = 9%) range. In one product photoinstability became significant in the UVA range at higher UV exposures. CONCLUSIONS: Out of 27 lipsticks only 13 products showed a photostable performance (DeltaTA < 5% and DeltaTB < 5% for 12.5 SED). We propose therefore that only products, which fulfil these UV photostability criteria should be marketed.

Does the weather influence the occurrence of abomasal displacement in dairy cows?

Aim of the study was to investigate the correlation between the occurrence of abomasal displacement and the weather situations. Data were collected for the years 2000 and 2001 in the area around Lisbon at 26 farms keeping about 6500 Holstein-Friesian milk cows; the analysis of 372 cases of abomasal displacement were included in the study. The weather situation was assessed on daily basis: atmospheric pressure, relative humidity, precipitation, daily insolation, maximum air temperature, minimum air temperature and average wind velocity. These original parameters were modified for the statistical analyses according to atmospheric pressure, water vapour pressure, relative humidity, temperature, temperature range, precipitation, insolation and wind speed. The change of the weather situation was described by the mean absolute deviation (deviation of the meteorological parameters from the running mean over a period of 5 and 10 days) and by a method which was based on the principal component analysis of the entire data set. A weak influence of water vapour pressure, relative humidity, temperature, temperature range, precipitation, and insolation on the occurrence of abomasal displacements was found by linear correlation- and regression analysis. A higher probability for abomasal displacement was verified for low water vapour pressure, high relative humidity, low air temperature, low temperature range, high precipitation and low insolation. No statistically significant relations were found between occurrence of abomasal displacement and either wind velocity or atmospheric pressure. A time series analysis exhibited a higher prevalence for abomasal displacement for periods with a change from sunny, warm and dry days to cool, overcast and humid days. From the present work it can be concluded that the meteorological situation has an influence on the occurrence of abomasal displacement. Therefore, the weather situation should be included among the predisposing causes of the occurrence of abomasal displacements.

Assessment of thickness of photoprotective lipsticks and frequency of reapplication: results from a laboratory test and a field experiment.

BACKGROUND: The thickness of the sunscreen layer that is actually applied by consumers under usual conditions has been determined for photoprotective lotions and creams; however, this question is still unanswered for photoprotective lipsticks. OBJECTIVES: To assess lipstick thickness (area density) and frequency of application per day for two commercially available photoprotective lipsticks with different consistency. METHODS: The study consisted of a laboratory test and a field experiment. In the laboratory test the applied lipstick thickness was determined as area density in mg cm(-2) for a group of 28 panellists under standardized conditions. In a separate group of 18 subjects we assessed the area density and the frequency of application per day for two photoprotective lipsticks during a 6-day skiing course. RESULTS: In the laboratory test the median and 95% confidence interval of the area density was 0.98 mg cm(-2) (0.66-1.65) and 0.86 mg cm(-2) (0.63-1.40) for products A and B, respectively. The respective values of the field experiment were 1.58 mg cm(-2) (0.79-2.23) (product A) and 1.76 mg cm(-2) (1.16-3.50) (product B). Only 11% of all applications of lipstick A and 6% of all applications of lipstick B reached the reference area density of 2.0 mg cm(-2). The difference between the median of the area density for lipstick A (firm consistency) and lipstick B (soft consistency) was not statistically significant. No statistically significant influence on the area density was found for age, sex, photobiological skin type or regular lipstick use. The median daily frequency of application was 2.2 times for lipstick A and 3.0 times for lipstick B. CONCLUSION: Our investigation shows that photoprotective lipsticks are applied in a much thinner layer than recommended by international standards (2 mg cm(-2)). This results in a significant reduction of the photoprotective capacity. Furthermore, the frequency of application is too low for adequate protection. Therefore, we propose that the sun protection factor (SPF) should be assessed for an area density that reflects the actual usage patterns. As long as the test protocol is not adapted to the reduced area density, photoprotective lipsticks with high and ultrahigh SPF should be recommended, especially for individuals with increased risk for the development of lip malignancies.

Change of ultraviolet absorbance of sunscreens by exposure to solar-simulated radiation.

Regarding the outdoor behavior of the Caucasian population, modern sunscreens should provide high and broad-spectrum ultraviolet protection in the ultraviolet B as well as in the ultraviolet A range and should be photochemically stable for ultraviolet doses, which can be expected in solar radiation. At present an assessment of the photostability of suncare products is not a general requirement before marketing. In order to evaluate the photostability of suncare products we conducted an in vitro test and measured the spectral absorbance of 16 sunscreens before, and after exposure to increasing biologically weighted standard erythema doses (5, 12.5, 25, 50) of solar-simulated radiation. Seven of 16 suncare products showed a significant dose- and wavelength-dependent decrease of the ultraviolet A protective capacity, whereas the ability to absorb ultraviolet B was not affected. In the ultraviolet A range, the decrease of absorbance (photoinactivation), respectively, the increase of transmission was 12-48% for an ultraviolet exposure of 25 standard erythema dose. Photoinactivation started in the wavelength range between 320 and 335 nm with a maximum above 350 nm. Furthermore, our analysis showed that the behavior of suncare products was not predictable from its individual ingredients. Neither complex combinations of organic filters nor addition of inorganic filters could absolutely prevent photoinactivation. The inclusion of a single photounstable filter did not mean photoinstability of the complete suncare product. Photoinactivation of sunscreens appears to be an underestimated hazard to the skin, first, by formation of free radicals, second, by increased ultraviolet A transmission.

Predicting odour impact using the Austrian odour dispersion model (AODM).

Using a dispersion model to calculate ambient odour concentrations, the separation distance between livestock buildings and residential areas is defined by the odour impact criteria using a combination of a pre-selected odour threshold and an exceeding probability. The dynamic Austrian Odour Dispersion Model (AODM), a Gaussian model, is used to calculate the direction-dependent separation distances for several combinations of these two values, which represent the protection level of various land use categories. The calculated direction-dependent separation distances are a function of the prevailing wind velocity and atmospheric stability conditions. At a site in the Austrian North-alpine foreland, the direction-dependent separation distance (calculated on the basis of a two year time series of meteorological data) for pure residential areas (3% exceeding probability over the year for an odour threshold of 1 OU/m3) lies between 99 m (for northerly winds with a probability of less than 3%) and 362 m (for westerly winds with a probability of 34%). For west and east the main wind directions, odour sensation can be expected more often for higher wind velocities and a neutral or stable atmosphere around sunset. Northerly and southerly winds show the typical diurnal variation of a local valley wind system with predominantly northerly daytime up-valley and southerly night-time down-valley winds.

Steady-state balance model to calculate the indoor climate of livestock buildings, demonstrated for finishing pigs.

The indoor climate of livestock buildings is of importance for the well-being and health of animals and their production performance (daily weight gain, milk yield etc). By using a steady-state model for the sensible and latent heat fluxes and the CO2 and odour mass flows, the indoor climate of mechanically ventilated livestock buildings can be calculated. These equations depend on the livestock (number of animals and how they are kept), the insulation of the building and the characteristics of the ventilation system (ventilation rate). Since the model can only be applied to animal houses where the ventilation systems are mechanically controlled (this is the case for a majority of finishing pig units), the calculations were done for an example of a finishing pig unit with 1,000 animal places. The model presented used 30 min values of the outdoor parameters temperature and humidity, collected over a 2-year period, as input. The projected environment inside the livestock building was compared with recommended values. The duration of condensation on the inside surfaces was also calculated.

Comparison of models used for UV index calculations.

Eighteen radiative transfer models in use for calculation of UV index are compared with respect to their results for more that 100 cloud-free atmospheres, which describe present, possible future and extreme conditions. The comparison includes six multiple-scattering spectral models, eight fast spectral models and four empirical models. Averages of the results of the six participating multiple-scattering spectral models are taken as a basis for assessment. The agreement among the multiple-scattering models is within +/- 0.5 UV index values for more than 80% of chosen atmospheric parameters. The fast spectral models have very different agreement, between +/- 1 and up to 12 UV index values. The results of the empirical models agree reasonably well with the reference models but only for the atmospheres for which they have been developed. The data to describe the atmospheric conditions, which are used for the comparison, together with the individual results of all participating models and model descriptions are available on the Internet: http://www.meteo.physik.uni-muenchen.de/++ +strahlung/cost/.

[Human behavior in the solar radiation field with reference to ultraviolet exposure]. / Das Verhalten des Menschen im solaren Strahlungsfeld im Hinblick auf seine UV-Exposition.

There is a causal relation between solar ultraviolet radiation and skin cancer. For epidemiological investigations, quantification of the UV exposure is essential. To set up a risk assessment for the whole population, a representative survey was performed in Austria. The questionnaire refers to three sectors of everyday life: work, recreation and holidays; in addition the use of solaria is asked about for a further investigation. The UV exposure caused by humans' behaviour in the field of solar radiation was analysed from various demographic aspects. For some subpopulations the UV exposure sustained during work, recreation and holidays was compared. Groups with high occupational UV exposure show a weaker tendency to stay outdoors during leisure time and holidays than groups characterized by high UV exposure in their leisure time, who also prefer sun-intensive activities during holidays.

Trend analysis of solar ultraviolet exposure of the Austrian population caused by holiday patterns since 1969.

Over the last few decades, a steady increase in the incidence of skin cancer has been observed. Solar ultraviolet (UV) exposure is undoubtedly one of the primary causes, and of these, holiday patterns are an intrinsic component. To assess solar UV exposure for this trend analysis, changes in holiday patterns were investigated. For Austrians, a preponderance of holidays are spent at the Mediterranean Sea. These holidays represent not only a potentially high UV exposure because of location but also because sun-intensive activities are preferred. The analysis shows an increase in solar UV exposure from all holidays of 1.6% per year. About 22% of the population spends holidays at the Mediterranean Sea, and UV exposure of the total population from these holidays has increased annually by about 3.3%. Because of the latency period, it is not possible to draw conclusions from the increase in UV exposure and the temporal trends in skin cancer. A longer time series would be necessary to do this. A direct comparison of data from other countries reporting increases in skin cancer does not seem appropriate, as levels of UV exposure vary greatly and such factors as genetic susceptibility are involved.

Model for the global irradiance of the solar biologically-effective ultraviolet-radiation on inclined surfaces.

The body surface area of man is the relevant receiving surface for solar UV radiation. To consider this body surface geometry, the biologically-effective UV radiation of the solar global radiation was measured. This was done at 26 differently aligned measuring points whose orientation was determined by the angle of inclination (vertical) and the azimuth (horizontal). Approximately eight hundred sets of measurement series were carried out at 33 different sites. A simple model, developed from the data obtained, made it possible to calculate relative irradiance as a function of the angle of inclination and the ground reflection (UV albedo). Thus relative risk of solar UV exposure to different regions of the body can be assessed. In addition to this, if the irradiance on a horizontal plane (measured or calculated by a corresponding model) is taken into consideration, the absolute values for UV irradiance on tilted planes can be determined.

Effect of topical solvents on ultraviolet B erythema.

The skin of subjects was pretreated with 3 solvents, normal saline, 95% ethanol and diethylether. No significant difference in erythemal sensitivity to UVB was demonstrated for any of the solvents.

[UV-inactivation of microorganisms in water]. / UV-Inaktivierung von Mikroorganismen in Wasser.

UV-Inactivation of Escherichia coli, Bacillus subtilis spores, Staphylococcus-Phage A 994, Poliovirus type Mahoney and Rotavirus SA 11 was tested under controlled physical conditions. B. subtilis-spores were found to be the most resistant of these microorganisms, followed by Rotavirus, Bacteriophage and Poliovirus. E. coli required the lowest irradiation dose for inactivation. Causes and meaning of these dose-survival-reactions are discussed.

[Computer simulation of the stable climate on the PC in veterinary practice]. / Computersimulation des Stallklimas am PC in der tierärztlichen Praxis.

The wide distribution of personal computers allows the application of programs which enable veterinary surgeons to assist in the management of live stock. A simulation model is made for the field of indoor climates of stables which makes a full-year calculation of temperature and humidity of the indoor climate and the quality of the air in stables. The calculation is based on a steady-state balance model of energy (heat and humidity) and matter. Using the example of a pig fattening sty, all the necessary system parameters are stated that are needed to totally present the model. The results of the simulation are then interpreted. Furthermore the assertions and conclusions will be shown which result thereby.