Prevention of work-related airway allergies; summary of the advice from the Health Council of the Netherlands.

The Health Council of the Netherlands published a report in which the best procedure and method for recommending health-based occupational exposure limits (OELs) for inhaled allergens were identified by evaluating the scientific state of the art. Many respiratory disorders in the workplace arise from inhalation of substances which can cause allergy. To protect workers against respiratory allergy, various preventive measures are taken, one of them being reduction of exposure by setting legally binding standards. These are based on health-based OELs that specify a level of exposure to an airborne substance, a threshold level, below which it may reasonably be expected that there is no risk of adverse health effects. The Council is of the opinion that an OEL should prevent against allergic sensitization, as sensitization plays a crucial biological role and is a prerequisite for the development of allergy. Furthermore, the Council considers it most likely that the exposure level below which no allergic sensitization develops for most allergens is so low, that OELs are difficult to set with the current knowledge and technical feasibilities. An alternative approach is to accept exposure, which carries a small predefined risk in developing allergic sensitization. In addition, it is worth considering periodic screening of exposed workers on allergic sensitization, because timely intervention can prevent worse. The feasibility of periodic screening and what else is needed to comply with the most important criteria, should however be judged case-by-case.

Viscous stabilization of 2D drainage displacements with trapping

We investigate the stabilization mechanisms due to viscous forces in the invasion front during drainage displacement in two-dimensional porous media using a network simulator. We find that in horizontal displacement the capillary pressure difference between two different points along the front varies almost linearly as a function of height separation in the direction of the displacement. The numerical result supports arguments taking into account the loopless displacement pattern where nonwetting fluid flows in separate strands (paths). As a consequence, we show that existing theories developed for viscous stabilization are not compatible with drainage when loopless strands dominate the displacement process.

Modulation of horizontal cell receptive fields in the light adapted goldfish retina.

In the isolated goldfish retina, 700 nm background illumination increases the horizontal cell receptive field size, as measured with 565 nm slits of light, but decreases the receptive field size, when measured with 660 nm slits. These background-induced changes in receptive field size are absent when the depolarizing responses in bi- and triphasic horizontal cells are blocked by lowering the [Ca2+] in the Ringer's solution from 1.0 to 0.1 mM. These results cannot be explained by the linear properties of the horizontal cell layers, nor by slow adaptational processes, but are consistent with the concept that feedback from horizontal cells to cones modifies the horizontal cell receptive field properties.

Effect of parenteral testosterone therapy on penile development in boys with hypospadias.

Forty boys with hypospadias received 2 mg/kg testosterone esters intramuscularly 5 and 2 weeks before surgical correction of the hypospadias. The effects on penile development were determined 3 and 5 weeks after the first injection and 3 and 12 months post-operatively. A significant effect on penile development was shown. This effect disappeared during the first year following treatment. There was no effect on bone maturation, children's height and the ultimate testosterone level. All adverse effects disappeared after cessation of therapy. Androgen receptor deficiency as a possible cause of hypospadias is not supported by our observations.