Maternal serum interleukin-1β, -6 and -8 levels and potential determinants in pregnancy and peripartum

Aims: To measure maternal serum interleukins (IL) in pregnancy, delivery and early puerperium, and to identify their potential determinants. Methods: Prospective longitudinal measures of serum IL-1β, IL-6 and IL-8 in 38 healthy pregnant women at antenatal visits, through labor and delivery, with clinical correlates (infection, vaginal hemorrhage and anemia) recorded by questionnaire. Results: Pregnancy IL levels remained consistently low. IL-1β increased shortly before delivery, then returned to pregnant levels, except where blood loss exceeded 500 ml. IL-6 and IL-8 rose at labor onset and exceeded pregnancy levels through postpartum day three. Postpartum IL-6 was higher after non-elective cesarean section than after spontaneous delivery (P < 0.0001), and where blood loss exceeded 500 ml. IL-6 and IL-8 were higher with systemic infection during delivery (P < 0.0001) and on postpartum day one (P < 0.05); IL-8 was higher in anemia (delivery: P < 0.005; postpartum day 1: P < 0.05). Differences due to delivery mode and systemic infection remained significant after correction for other conditions. Conclusions: Labor-dependent inflammation increases all IL levels at delivery. Further studies with larger sample sizes are required to establish reference values differentiating physiology from pathology as an aid to peripartum managemen

PCB 47, 51, 68 – Bestimmung von PCB 47, 51, 68 in der Luft am Arbeitsplatz mittels Gaschromatographie (GC-ECD)

This analytical method is a validated measurement procedure for the determination of the three tetrachlorinated biphenyls PCB 47 [2437-79-8], PCB 51 [68194-04-7] and PCB 68 [73575-52-7] in workplace air in a concentration range of 0.16 to 0.62 μg/m3. It was developed to detect PCB that only may be generated during the manufacture of silicone products with peroxidic crosslinking with bis(2,4-dichlorobenzoyl) peroxide. By measurement in manufacturing plants it could be proven that the PCB to be investigated are present exclusively in vapour form. For this reason, the method was only validated for vaporous samples. There are currently no valid evaluation criteria for these PCB. Therefore, the German Occupational Exposure Limit Value for the sum of all PCB (5 × sum of the 6 indicator PCB [28, 52, 101, 138, 152, 180]) of 3 μg/m3 was used as the assessment standard for each congener. For sampling, a defined volume of air is drawn through a sorbent tube filled with Florisil. The flow rate is set to 1 l/min and sampling duration is 4 hours (which correspond to a sampling volume of 240 l). The PCB are extracted with n-hexane at 40 °C in an ultrasonic bath and subsequently analysed using gas chromatography with electron capture detection. The quantitative determination is based on a calibration function. The limit of quantification is 0.11 μg/m3 based on an air sample volume of 240 l. The mean recovery is 96% and the expanded uncertainty for the validation range of 0.16 to 0.62 μg/m3 is 22 to 24%

BACE1 activity regulates cell surface contactin-2 levels

Background: Although BACE1 is a major therapeutic target for Alzheimer’s disease (AD), potential side effects of BACE1 inhibition are not well characterized. BACE1 cleaves over 60 putative substrates, however the majority of these cleavages have not been characterized. Here we investigated BACE1-mediated cleavage of human contactin-2, a GPI-anchored cell adhesion molecule. Results: Our initial protein sequence analysis showed that contactin-2 harbors a strong putative BACE1 cleavage site close to its GPI membrane linker domain. When we overexpressed BACE1 in CHO cells stably transfected with human contactin-2, we found increased release of soluble contactin-2 in the conditioned media. Conversely, pharmacological inhibition of BACE1 in CHO cells expressing human contactin-2 and mouse primary neurons decreased soluble contactin-2 secretion. The BACE1 cleavage site mutation 1008MM/AA dramatically impaired soluble contactin-2 release. We then asked whether contactin-2 release induced by BACE1 expression would concomitantly decrease cell surface levels of contactin-2. Using immunofluorescence and surface-biotinylation assays, we showed that BACE1 activity tightly regulates contactin-2 surface levels in CHO cells as well as in mouse primary neurons. Finally, contactin-2 levels were decreased in Alzheimer’s disease brain samples correlating inversely with elevated BACE1 levels in the same samples. Conclusion: Our results clearly demonstrate that mouse and human contactin-2 are physiological substrates for BACE1. BACE1-mediated contactin-2 cleavage tightly regulates the surface expression of contactin-2 in neuronal cells. Given the role of contactin-2 in cell adhesion, neurite outgrowth and axon guidance, our data suggest that BACE1 may play an important role in these physiological processes by regulating contactin-2 surface levels

Acrylonitrile – Determination of acrylonitrile in workplace air using gas chromatography (GC-MS)

This analytical method is a validated measurement procedure for the determination of acrylonitrile [107-13-1] after personal or stationary sampling. Sampling is performed by drawing a defined volume of air through an adsorption tube made of stainless steel packed with Chromosorb 106 using a suitable flow-regulated pump. After thermal desorption, the acrylonitrile retained on the adsorbent is analysed using gas chromatography with flame ionisation detection and mass spectrometry. The relative limit of quantification (LOQ) is 0.0042 mg acrylonitrile/m3 for an air sample volume of 2.4 l. The mean recovery for acrylonitrile was 104%. The concentration-dependent expanded uncertainty was 26.0% to 26.6%. This analytical method has been accredited by the accident insurance companies for the detection in workplace air of substances that are carcinogenic, mutagenic or toxic to reproduction. This method has been tested and recommended for the determination of acrylonitrile in work areas by the GermanSocial Accident Insurance (DGUV). Both personal and stationary sampling can be performed for measurements in order to evaluate work area

1,2-Dichloroethane – Method for the determination of 1,2-dichloroethane in workplace air using gas chromatography (GC-MS)

This analytical method is a validated measurement procedure for the determination of 1,2-dichloroethane [107-06-2] after personal or stationary sampling. Sampling is performed by drawing a defined volume of air through an adsorption tube made of stainless steel packed with Chromosorb 106 using a suitable flow-regulated pump. After thermal desorption, the 1,2-dichloroethane retained on the adsorbens is analysed using gas chromatography with flame ionisation detection and mass spectrometry. The relative limit of quantification (LOQ) is 0.009 mg 1,2-dichloroethane/m3 for an air sample volume of 1.2 l. The mean recovery for 1,2-dichloroethane was 101%. The concentration-dependent expanded uncertainty was 20% to 21%. This analytical method has been accredited by the accident insurance companies for the detection in workplace air of substances that are carcinogenic, mutagenic or toxic to reproduction. This method has been tested and recommended for the determination of 1,2-dichloroethane in work areas by the German Social Accident Insurance (DGUV). Both personal and stationary sampling can be performed for measurements in order to evaluate work areas