DHEA inhibits acute microglia-mediated inflammation through activation of the TrkA-Akt1/2-CREB-Jmjd3 pathway.

Dehydroepiandrosterone (DHEA) is the most abundant circulating steroid hormone in humans, produced by the adrenals, the gonads and the brain. DHEA was previously shown to bind to the nerve growth factor receptor, tropomyosin-related kinase A (TrkA), and to thereby exert neuroprotective effects. Here we show that DHEA reduces microglia-mediated inflammation in an acute lipopolysaccharide-induced neuro-inflammation model in mice and in cultured microglia in vitro. DHEA regulates microglial inflammatory responses through phosphorylation of TrkA and subsequent activation of a pathway involving Akt1/Akt2 and cAMP response element-binding protein. The latter induces the expression of the histone 3 lysine 27 (H3K27) demethylase Jumonji d3 (Jmjd3), which thereby controls the expression of inflammation-related genes and microglial polarization. Together, our data indicate that DHEA-activated TrkA signaling is a potent regulator of microglia-mediated inflammation in a Jmjd3-dependent manner, thereby providing the platform for potential future therapeutic interventions in neuro-inflammatory pathologies.

Determination of cyclic volatile methylsiloxanes in personal care products by gas chromatography.

OBJECTIVE: Organosiloxanes are prevalent in personal care products (PCPs) due to the desired properties they impart in the usage and application of such products. However, the European Chemical Agency (ECHA) has recently published restriction proposals on the amount of two cyclic siloxanes, octamethylcyclotetrasiloxane (D4) and decamethylcyclotetrasiloxane (D5), allowed in wash off products such as shampoos and conditioners which are discharged down the drain during consumer use. This legislation will require that reliable analytical methods are available for manufacturers and government agencies to use in documenting compliance with the restrictions. This article proposes a simple analytical method to enable accurate measurement of these compounds down to the circa 0.1 weight per cent level in PCPs. METHODS: Although gas chromatography methods are reported in the literature for quantitation of D4 and D5 in several matrices including PCPs, the potential for generation of false positives due to contamination, co-elution and in situ generation of cyclic volatile methylsiloxanes (cVMS) is always present and needs to be controlled. This report demonstrates the applicability of using a combination of emulsion break, liquid-liquid extraction and silylation sample preparation followed by GC-FID analysis as a suitable means of analysing PCPs for specific cVMS. RESULTS: The reliability and limitations of such methodology were demonstrated through several round-robin studies conducted in the laboratories of a consortium of silicone manufacturers. In addition, this report presents examples of false positives encountered during development of the method and presents a comparative analysis between this method and a published QuEChERS sample preparation procedure to illustrate the potential for generation of false positives when an inappropriate approach is applied to determination of cVMS in personal care products. CONCLUSION: This report demonstrates that an approach to determine cVMS levels in personal care products is to perform an emulsion break on the sample, isolate the non-polar phase from the emulsion break and treat with a silylation reagent to abate potential in situ formation of cyclics during the course of GC-FID analysis. Round-robin studies conducted in laboratories representing multiple siloxane manufacturers demonstrated the reliability of the GC-FID method when measuring cVMS in PCPs down to circa 0.1%.

Antihypertensive and cardioprotective effects of the dipeptide isoleucine-tryptophan and whey protein hydrolysate.

AIMS: Angiotensin-converting enzyme inhibitors are treatment of choice in hypertensive patients. Clinically used inhibitors exhibit a structural similarity to naturally occurring peptides. This study evaluated antihypertensive and cardioprotective effects of ACE-inhibiting peptides derived from food proteins in spontaneously hypertensive rats. METHODS AND RESULTS: Isoleucine-tryptophan (in vitro IC50 for ACE = 0.7 µm), a whey protein hydrolysate containing an augmented fraction of isoleucine-tryptophan, or captopril was given to spontaneously hypertensive rats (n = 60) over 14 weeks. Two further groups, receiving either no supplement (Placebo) or intact whey protein, served as controls. Systolic blood pressure age-dependently increased in the Placebo group, whereas the blood pressure rise was effectively blunted by isoleucine-tryptophan, whey protein hydrolysate and captopril (-42 ± 3, -38 ± 5, -55 ± 4 mm Hg vs. Placebo). At study end, myocardial mass was lower in isoleucine-tryptophan and captopril groups but only partially in the hydrolysate group. Coronary flow reserve (1 µm adenosine) was improved in isoleucine-tryptophan and captopril groups. Plasma ACE activity was significantly decreased in isoleucine-tryptophan, hydrolysate and captopril groups, but in aortic tissue only after isoleucine-tryptophan or captopril treatment. This was associated with lowered expression and activity of matrix metalloproteinase-2. Following isoleucine-tryptophan and captopril treatments, gene expression of renin was significantly increased indicating an active feedback within renin-angiotensin system. CONCLUSION: Whey protein hydrolysate and isoleucine-tryptophan powerfully inhibit plasma ACE resulting in antihypertensive effects. Moreover, isoleucine-tryptophan blunts tissue ACE activity, reduces matrix metalloproteinase-2 activity and improves coronary flow reserve. Thus, whey protein hydrolysate and particularly isoleucine-tryptophan may serve as innovative food additives with the goal of attenuating hypertension.

Conservation of DNA methylation in dipteran insects.

DNA methylation is a central mechanism of epigenetic regulation. Whereas vertebrate DNA methylation requires at least four different DNA methyltransferases, Drosophila melanogaster only utilizes a single, Dnmt2-like enzyme. This profound difference has raised the question of the evolutionary significance of the Drosophila methylation system. We have now identified Dnmt2-like open reading frames in the genome sequences of Drosophila pseudoobscura and Anopheles gambiae. These genes represent the only candidate DNA methyltransferases in their respective genomes. Consistent with a catalytic activity of Dnmt2 proteins, we could also demonstrate low but significant levels of DNA methylation in genomic DNA from these species. Lastly, we were also able to detect highly conserved Dnmt2-like open reading frames and concomitant DNA methylation in several additional Drosophila species, which suggests that Dnmt2-mediated DNA methylation has been conserved over a considerable evolutionary distance.

[Heart rate and heart rhythm in healthy infants and children]. / Herzfrequenz und Herzrhythmus bei gesunden Säuglingen und Kindern.

Cardiac rate and rhythm in 141 healthy infants, toddlers and schoolchildren during 24 hour ambulatory electrocardiographic monitoring are reported. Maximal and minimal heart rate (1/min) in infants 1 to 5 months of age were 204 +/- 17 and 105 +/- 13, in infants 6 to 12 months of age 187 +/- 19 and 101 +/- 15; in toddlers 177 +/- 17 and 66 +/- 10; in schoolchildren 158 +/- 24 and 54 +/- 6. A sizeable proportion of children of all age groups showed patterns of sinus arrhythmias indistinguishable from second degree sinuatrial block. Supraventricular escape beats and escape rhythms were frequent as well. The longest RR interval was 1.03 +/- 0.16 sec. in infants, 1.20 +/- 0.25 sec. in toddlers, and 1.35 +/- 0.15 sec., respectively, in schoolchildren. Two % of infants, 7% of toddlers, and 6% of schoolchildren had episodes of second degree atrioventricular block type I (Wenckebach) at rest. Supraventricular extrasystoles were found in 38%, 13% and 26%, respectively, and uniform ventricular extrasystoles in 18%, 20% and 16%, respectively, of infants, toddlers and schoolchildren. These data, together with similar information in the literature, can be taken as basis for the evaluation of ambulatory electrocardiograms in children.