Fatty acid distribution of cord and maternal blood in human pregnancy: special focus on individual trans fatty acids and conjugated linoleic acids

<p>Abstract</p> <p>Background</p> <p>Maternal nutrition in pregnancy has a crucial impact on the development of the fetus. Dietary <it>trans </it>fatty acids (<it>t</it>FA) are known to have adverse health effects, especially during pregnancy. However, the distribution of <it>t</it>FA produced via partial hydrogenation of vegetable oils (mainly elaidic acid; <it>t</it>9) differs compared to ruminant-derived <it>t</it>FA (mainly vaccenic acid; <it>t</it>11). Recent findings indicate that they may have different impact on human health.</p> <p>Therefore, in this study, plasma and erythrocytes of mother-child pairs (n = 55) were sampled to investigate the distribution of <it>t</it>FA, including individual <it>trans </it>C18:1 fatty acids and conjugated linoleic acids (CLA) in fetal related to maternal lipids; with additional consideration of maternal dairy fat intake.</p> <p>Results</p> <p>Portion of <it>t</it>9 and <it>t</it>11, but also of <it>c</it>9,<it>t</it>11 CLA was higher in maternal than in fetal blood lipids. The portion of <it>t</it>9 in maternal and fetal lipids differed only slightly. In contrast, the portion of fetal <it>t</it>11 was only half of that in maternal blood. This led to a fetal <it>t</it>9/<it>t</it>11-index in plasma and erythrocytes being twice as high compared to the maternal values. A high dairy fat intake resulted in elevated portions of <it>t</it>11 and its Δ9-desaturation product <it>c</it>9,<it>t</it>11 CLA in maternal blood. In contrast, in the respective fetal blood lipids only <it>c</it>9,<it>t</it>11 CLA, but not <it>t</it>11 was increased. Nevertheless, a positive association between maternal and fetal plasma exists for both <it>t</it>11 and <it>c</it>9,<it>t</it>11 CLA. Furthermore, in contrast to <it>t</it>9, <it>t</it>11 was not negatively associated with n-3 LC-PUFA in fetal blood lipids.</p> <p>Conclusions</p> <p>Fetal blood fatty acid composition essentially depends on and is altered by the maternal fatty acid supply. However, in addition to dietary factors, other aspects also contribute to the individual fatty acid distribution (oxidation, conversion, incorporation). The lower portion of fetal <it>t</it>11 compared to maternal <it>t</it>11, possibly results from Δ9-desaturation to <it>c</it>9,<it>t</it>11 CLA and/or oxidation. Based on the fatty acid distribution, it can be concluded that <it>t</it>11 differs from <it>t</it>9 regarding its metabolism and their impact on fetal LC-PUFA.</p

Hydrophobic alkyl chains substituted to the 8-position of cyclic nucleotides enhance activation of CNG and HCN channels by an intricate enthalpy - entropy compensation

Cyclic nucleotide-gated (CNG) and hyperpolarization-activated cyclic nucleotide-gated (HCN) channels are tetrameric non-specific cation channels in the plasma membrane that are activated by either cAMP or cGMP binding to specific binding domains incorporated in each subunit. Typical apparent affinities of these channels for these cyclic nucleotides range from several hundred nanomolar to tens of micromolar. Here we synthesized and characterized novel cAMP and cGMP derivatives by substituting either hydrophobic alkyl chains or similar-sized more hydrophilic heteroalkyl chains to the 8-position of the purine ring with the aim to obtain full agonists of higher potency. The compounds were tested in homotetrameric CNGA2, heterotetrameric CNGA2:CNGA4:CNGB1b and homotetrameric HCN2 channels. We show that nearly all compounds are full agonists and that longer alkyl chains systematically increase the apparent affinity, at the best more than 30 times. The effects are stronger in CNG than HCN2 channels which, however, are constitutively more sensitive to cAMP. Kinetic analyses reveal that the off-rate is significantly slowed by the hydrophobic alkyl chains. Molecular dynamics simulations and free energy calculations suggest that an intricate enthalpy - entropy compensation underlies the higher apparent affinity of the derivatives with the longer alkyl chains, which is shown to result from a reduced loss of configurational entropy upon binding

Placental immune response to apple allergen in allergic mothers

The immunological milieu in the placenta may be crucial for priming the developing foetal immune system. Early imbalances may promote the establishment of immune-mediated diseases in later life, including allergies. The initial exposure to allergens seems to occur in utero, but little is known about allergen-induced placental cytokine and chemokine release. The release of several cytokines and chemokines from placenta tissue after exposure to mast cell degranulator compound 48/80 or apple allergen in placentas from allergic and healthy mothers was to be analysed. Four placentas from women with apple allergy and three controls were applied in a placental perfusion model with two separate cotyledons simultaneously perfused with and without apple allergen (Mal d 1). Two control placentas were perfused with compound 48/80. In outflow, histamine was quantified spectrophotofluorometrically, IL-2, IL-4, IL-6, IL-10, TNF and IFN-gamma by a cytometric multiplex bead array and IL-13 and CXCL10, CXCL11, CCL17 and CCL22 with an in-house multiplex Luminex assay. Compound 48/80 induced a rapid release of histamine, CXCL10, CXCL11, CCL17 and CCL22, but not of the other factors. Apple allergen induced a time-dependent release of IL-6 and TNF, but not of histamine, in placentas of women with apple allergy compared with the unstimulated cotyledon. CCL17 levels were slightly increased after allergen stimulation in control placentas. Allergens can induce placental cytokines and chemokines distinctly in allergic and healthy mothers. These mediators may affect the prenatal development of the immune system and modify the risk of diseases related to immune disorders in childhood such as allergies.Funding Agencies|Institut Danone (Haar, Germany); European Network of Excellence within the 6th Framework Programme of the European Union [512040]; Swedish Research Council [K2011-56X-21854-01-06]; Cancer and Allergy Association; Olle Engkvist Foundation</p

Novel Fluorescent Cyclic Nucleotide Derivatives to Study CNG and HCN Channel Function

A highly specific molecular interaction of diffusible ligands with their receptors belongs to the key processes in cellular signaling. Because an appropriate method to monitor the unitary binding events is still missing, most of our present knowledge is based on ensemble signals recorded from a big number of receptors, such as ion currents or fluorescence changes of suitably labeled receptors, and reasoning from these data to the ligand binding. To study the binding process itself, appropriately tagged ligands are required that fully activate the receptors and report the binding at the same time. Herein, we tailored a series of 18 novel fluorescent cyclic nucleotide derivatives by attaching 6 different dyes via different alkyl linkers to the 8-position of the purine ring of cGMP or cAMP. The biological activity was determined in inside-out macropatches containing either homotetrameric (CNGA2), heterotetrameric (CNGA2:CNGA4:CNGB1b), or hyperpolarization-activated cyclic nucleotide-modulated (HCN2) channels. All these novel fluorescent ligands are efficient to activate the channels, and the potency of most of them significantly exceeded that of the natural cyclic nucleotides cGMP or cAMP. Moreover, some of them showed an enhanced brightness when bound to the channels. The best of our derivatives bear great potential to systematically analyze the activation mechanism in CNG and HCN channels, at both the level of ensemble and single-molecule analyses

Uncoupling of Voltage- and Ligand-Induced Activation in HCN2 Channels by Glycine Inserts

Hyperpolarization-activated cyclic nucleotide-modulated (HCN) channels are tetramers that generate electrical rhythmicity in special brain neurons and cardiomyocytes. The channels are activated by membrane hyperpolarization. The binding of cAMP to the four available cyclic nucleotide-binding domains (CNBD) enhances channel activation. We analyzed in the present study the mechanism of how the effect of cAMP binding is transmitted to the pore domain. Our strategy was to uncouple the C-linker (CL) from the channel core by inserting one to five glycine residues between the S6 gate and the A′-helix (constructs 1G to 5G). We quantified in full-length HCN2 channels the resulting functional effects of the inserted glycines by current activation as well as the structural dynamics and statics using molecular dynamics simulations and Constraint Network Analysis. We show functionally that already in 1G the cAMP effect on activation is lost and that with the exception of 3G and 5G the concentration-activation relationships are shifted to depolarized voltages with respect to HCN2. The strongest effect was found for 4G. Accordingly, the activation kinetics were accelerated by all constructs, again with the strongest effect in 4G. The simulations reveal that the average residue mobility of the CL and CNBD domains is increased in all constructs and that the junction between the S6 and A′-helix is turned into a flexible hinge, resulting in a destabilized gate in all constructs. Moreover, for 3G and 4G, there is a stronger downward displacement of the CL-CNBD than in HCN2 and the other constructs, resulting in an increased kink angle between S6 and A′-helix, which in turn loosens contacts between the S4-helix and the CL. This is suggested to promote a downward movement of the S4-helix, similar to the effect of hyperpolarization. In addition, exclusively in 4G, the selectivity filter in the upper pore region and parts of the S4-helix are destabilized. The results provide new insights into the intricate activation of HCN2 channels

Surgical Aspects of Liver Transplantation and Domino Liver Transplantation in Maple Syrup Urine Disease: Analysis of 15 Donor‐Recipient Pairs

Liver transplantation (LT) has been shown to be a feasible treatment in patients with severe forms of maple syrup urine disease (MSUD). Because of a sufficient extrahepatic enzyme activity in non-MSUD individuals, the organ of MSUD patients can be used as a domino graft. We performed a retrospective data collection of all LTs for MSUD carried out at the University Medical Center Hamburg-Eppendorf (2016-2018). Moreover, data from all consecutive domino LTs of the MSUD grafts either transplanted at our institution or allocated to other transplant centers were analyzed. During the study period, 15 LTs in MSUD patients were performed (12 children, 3 adults; median age, 10.9 years; range, 0.3-26.1 years). Biliary complications occurred in 20%, and 13.3% suffered from bleeding complications. No further surgical problems occurred. At present, all MSUD patients are alive with a well-functioning liver graft and on an unrestricted diet. In total, 14 consecutive domino LTs were performed. No surgical complications requiring intervention occurred. One patient died because of HCC relapse, and all other patients are alive with good liver graft function. In conclusion, the use of MSUD livers as domino grafts is safe and allows application of LT in MSUD patients without net extraction of a liver graft from the limited donor pool

A high affinity switch for cAMP in the HCN pacemaker channels

Abstract Binding of cAMP to Hyperpolarization activated cyclic nucleotide gated (HCN) channels facilitates pore opening. It is unclear why the isolated cyclic nucleotide binding domain (CNBD) displays in vitro lower affinity for cAMP than the full-length channel in patch experiments. Here we show that HCN are endowed with an affinity switch for cAMP. Alpha helices D and E, downstream of the cyclic nucleotide binding domain (CNBD), bind to and stabilize the holo CNBD in a high affinity state. These helices increase by 30-fold cAMP efficacy and affinity measured in patch clamp and ITC, respectively. We further show that helices D and E regulate affinity by interacting with helix C of the CNBD, similarly to the regulatory protein TRIP8b. Our results uncover an intramolecular mechanism whereby changes in binding affinity, rather than changes in cAMP concentration, can modulate HCN channels, adding another layer to the complex regulation of their activity