Mast cell distribution in human carotid atherosclerotic plaque differs significantly by histological segment

Mast cells (MCs) are important contributors to atherosclerotic plaque progression. For prospective studies on mast cell contributions to plaque instability, the distribution of intraplaque MCs needs to be elucidated. Plaque stability is generally histologically assessed by dividing the plaque specimen into segments to be scored on an ordinal scale. However, owing to competitive use, studies may have to deviate to adjacent segments, yet intersegment differences of plaque characteristics, especially MCs, are largely unknown. Therefore, the hypothesis that there is no segment to segment difference in MC distribution between atherosclerotic plaque segments was tested, and intersegment associations between MCs and other plaque characteristics was investigated.\nTwenty-six carotid atherosclerotic plaques from patients undergoing carotid endarterectomy included in the Athero-Express Biobank were analysed. The plaque was divided in 5 mm segments, differentiating between the culprit lesion (segment 0), adjacent segments (-1/+1) and more distant segments (-2/+2) for the presence of MCs. The associations between the intersegment distribution of MCs and smooth muscle cells, macrophage content, and microvessel density in the culprit lesion were studied.\nA statistically significant difference in MCs/mm2 between the different plaque segments (p 2 between the culprit and adjacent segment (p = .037) and between the culprit lesion and the more distant segment (p 2 in multiple different segments were positively correlated with microvessel density and macrophage content in the culprit lesion.\nMC numbers reveal significant intersegment differences in human carotid plaques. Future histological studies on MCs should use a standardised segment for plaque characterisation as plaque segments cannot be used interchangeably for histological MC analyses.Biopharmaceutic

An acidic model pro-peptide affects the secondary structure, membrane interactions and antimicrobial activity of a crotalicidin fragment

In order to study how acidic pro-peptides inhibit the antimicrobial activity of antimicrobial peptides, we introduce a simple model system, consisting of a 19 amino-acid long antimicrobial peptide, and an N-terminally attached, 10 amino-acid long acidic model pro-peptide. The antimicrobial peptide is a fragment of the crotalicidin peptide, a member of the cathelidin family, from rattlesnake venom. The model pro-peptide is a deca (glutamic acid). Attachment of the model pro-peptide only leads to a moderately large reduction in the binding to- and induced leakage of model liposomes, while the antimicrobial activity of the crotalicidin fragment is completely inhibited by attaching the model pro-peptide. Attaching the pro-peptide induces a conformational change to a more helical conformation, while there are no signs of intra- or intermolecular peptide complexation. We conclude that inhibition of antimicrobial activity by the model pro-peptide might be related to a conformational change induced by the pro-peptide domain, and that additional effects beyond induced changes in membrane activity must also be involved.</p

Associations of autozygosity with a broad range of human phenotypes

In many species, the offspring of related parents suffer reduced reproductive success, a phenomenon known as inbreeding depression. In humans, the importance of this effect has remained unclear, partly because reproduction between close relatives is both rare and frequently associated with confounding social factors. Here, using genomic inbreeding coefficients (F-ROH) for >1.4 million individuals, we show that F-ROH is significantly associated (p <0.0005) with apparently deleterious changes in 32 out of 100 traits analysed. These changes are associated with runs of homozygosity (ROH), but not with common variant homozygosity, suggesting that genetic variants associated with inbreeding depression are predominantly rare. The effect on fertility is striking: F-ROH equivalent to the offspring of first cousins is associated with a 55% decrease [95% CI 44-66%] in the odds of having children. Finally, the effects of F-ROH are confirmed within full-sibling pairs, where the variation in F-ROH is independent of all environmental confounding.Peer reviewe

Implicating genes, pleiotropy, and sexual dimorphism at blood lipid loci through multi-ancestry meta-analysis

Funding Information: GMP, PN, and CW are supported by NHLBI R01HL127564. GMP and PN are supported by R01HL142711. AG acknowledge support from the Wellcome Trust (201543/B/16/Z), European Union Seventh Framework Programme FP7/2007–2013 under grant agreement no. HEALTH-F2-2013–601456 (CVGenes@Target) & the TriPartite Immunometabolism Consortium [TrIC]-Novo Nordisk Foundation’s Grant number NNF15CC0018486. JMM is supported by American Diabetes Association Innovative and Clinical Translational Award 1–19-ICTS-068. SR was supported by the Academy of Finland Center of Excellence in Complex Disease Genetics (Grant No 312062), the Finnish Foundation for Cardiovascular Research, the Sigrid Juselius Foundation, and University of Helsinki HiLIFE Fellow and Grand Challenge grants. EW was supported by the Finnish innovation fund Sitra (EW) and Finska Läkaresällskapet. CNS was supported by American Heart Association Postdoctoral Fellowships 15POST24470131 and 17POST33650016. Charles N Rotimi is supported by Z01HG200362. Zhe Wang, Michael H Preuss, and Ruth JF Loos are supported by R01HL142302. NJT is a Wellcome Trust Investigator (202802/Z/16/Z), is the PI of the Avon Longitudinal Study of Parents and Children (MRC & WT 217065/Z/19/Z), is supported by the University of Bristol NIHR Biomedical Research Centre (BRC-1215–2001) and the MRC Integrative Epidemiology Unit (MC_UU_00011), and works within the CRUK Integrative Cancer Epidemiology Programme (C18281/A19169). Ruth E Mitchell is a member of the MRC Integrative Epidemiology Unit at the University of Bristol funded by the MRC (MC_UU_00011/1). Simon Haworth is supported by the UK National Institute for Health Research Academic Clinical Fellowship. Paul S. de Vries was supported by American Heart Association grant number 18CDA34110116. Julia Ramierz acknowledges support by the People Programme of the European Union’s Seventh Framework Programme grant n° 608765 and Marie Sklodowska-Curie grant n° 786833. Maria Sabater-Lleal is supported by a Miguel Servet contract from the ISCIII Spanish Health Institute (CP17/00142) and co-financed by the European Social Fund. Jian Yang is funded by the Westlake Education Foundation. Olga Giannakopoulou has received funding from the British Heart Foundation (BHF) (FS/14/66/3129). CHARGE Consortium cohorts were supported by R01HL105756. Study-specific acknowledgements are available in the Additional file : Supplementary Note. The views expressed in this manuscript are those of the authors and do not necessarily represent the views of the National Heart, Lung, and Blood Institute; the National Institutes of Health; or the U.S. Department of Health and Human Services. Publisher Copyright: © 2022, The Author(s).Background: Genetic variants within nearly 1000 loci are known to contribute to modulation of blood lipid levels. However, the biological pathways underlying these associations are frequently unknown, limiting understanding of these findings and hindering downstream translational efforts such as drug target discovery. Results: To expand our understanding of the underlying biological pathways and mechanisms controlling blood lipid levels, we leverage a large multi-ancestry meta-analysis (N = 1,654,960) of blood lipids to prioritize putative causal genes for 2286 lipid associations using six gene prediction approaches. Using phenome-wide association (PheWAS) scans, we identify relationships of genetically predicted lipid levels to other diseases and conditions. We confirm known pleiotropic associations with cardiovascular phenotypes and determine novel associations, notably with cholelithiasis risk. We perform sex-stratified GWAS meta-analysis of lipid levels and show that 3–5% of autosomal lipid-associated loci demonstrate sex-biased effects. Finally, we report 21 novel lipid loci identified on the X chromosome. Many of the sex-biased autosomal and X chromosome lipid loci show pleiotropic associations with sex hormones, emphasizing the role of hormone regulation in lipid metabolism. Conclusions: Taken together, our findings provide insights into the biological mechanisms through which associated variants lead to altered lipid levels and potentially cardiovascular disease risk.Peer reviewe

Interfacial electrochemistry of colloidal ruthenium dioxide and catalysis of the photochemical generation of hydrogen from water

The formation of hydrogen from water using solar energy is a very attractive research topic, because of the potential use of hydrogen as an alternative, clean fuel. It has been shown by many workers in the field that photochemical hydrogen generation can be achieved in an aqueous system, containing a sensitizer (a light absorbing solute), an electron relay, and a dispersed catalyst. The electron relay transfers electrons from the light-excited sensitizer to the surface of the catalyst, where subsequent reduction of H +takes place. In an ideal photochemical system for solar energy conversion, water itself would ultimately provide the necessary electrons for hydrogen formation, under simultaneous oxygen evolution. However, complete ("cyclic") photodissociation of water involves a number of complications, like the recombination of intermediate photoproducts. To separately study the formation of hydrogen, these additional problems can be bypassed by adding an electron donor, which decomposes after having reduced the oxidized sensitizer. Such simplified systems are known as "sacrificial".The present thesis is concerned with the generation of hydrogen in such a sacrificial photochemical system. The main purpose has been to gain insight Into the processes that take place at the catalyst/solution interface. Because of its wide application in photochemical model systems for hydrogen production, methylviologen (MV 2+) was chosen as the electron relay. Via its reduced form MV +., electrons are transferred from the sensitizer to the catalyst. Colloidal ruthenium dioxide (RuO 2 ) was used as the catalyst compound. It has the advantage over the more commonly used Pt catalysts, that it does not catalyze the undesired, irreversible hydrogenation of MV 2+.The heterogeneous processes in a hydrogen photoproduction system cannot be investigated without taking into account the reactions in solution too. Therefore, ruthenium trisbipyridyl (Ru(bipy)32+) and EDTA were chosen as photosensitizer and sacrificial electron donor, respectively: most of the (light-induced) homogeneous reactions that take place in the Ru(bipy)32+/MV 2+/EDTA/colloidal catalyst system have been studied extensively by different groups of researchers. In our experiments, the standard reaction mixture (58 ml) for photogeneration of hydrogen contained 2 x 10 -4M Ru(bipy)32+, 5 x 10 -4M MV 2+, 0.02 M EDTA, and 0.05 M acetate buffer (pH 4.6).Colloidal RuO 2 was prepared by thermal decomposition of RuCl 3 at ca. 400 °C. The material obtained is crystalline and only slightly contaminated with residual Cl, which is mainly present at the surface of the particles. The BET surface area is 20-30 m 2/g. Dispersions of RuO 2 are colloid-chemically very unstable, even in the presence of polymers or surfactants. They manifest the same electric double layer characteristics as many other oxide dispersions. The point of zero charge (p.z.c.) in indifferent electrolyte (KNO 3 ) is positioned at pH 5.7-5.8.Experiments with RuO 2 film electrodes, prepared from the same colloidal material and sintered at 700 °C, revealed that the hydrogen evolution reaction is chemically reversible. Hydrogen evolution at moderate overpotentials does not modify the RuO 2 . In the presence of 0.05 M acetate buffer (pH 4.6), the mass transport limited current density for H +reduction is high since it is related to the buffer capacity and not to the actual proton activity. In the potential range studied, the hydrogen evolution reaction can be described by the Butler-Volmer equation, with a transfer coefficient&nbsp;αof about 0.33, and an exchange current density i o of ca. 0.09 mA/cm 2geometrical surface area. The true exchange current density is smaller by a factor depending on the surface roughness of the film electrodes.Adsorption, of MV 2+at the RuO 2 /solution interface is mainly a result of attractive coulombic interactions (above the p.z.c. of RuO 2 ), but it has been shown that there are also more specific interactions. However, the specific adsorption is weak and not noticeable at high concentrations of back-ground electrolyte and pH values below the p.z.c. of RuO 2 . No indications were found that MV 2+adsorbs at the catalyst surface under operational conditions of hydrogen evolution. Under these conditions, the sensitizer Ru(bipy)32+does not adsorb either. On the other hand, the electron donor EDTA strongly adsorbs on RuO 2 from a 0.05 M acetate buffer solution of pH 4.6. However, this seems not to affect the electron transfer between methylviologen and RuO 2 film electrodes, a process which takes place with a transfer coefficient&nbsp;αof ca. 0.35 and a standard heterogeneous rate constant k oof ca. 1.4 x 10 -5m/s (referred to the geometrical surface area).The colloidal RuO 2 turned out to be a good catalyst for photoproduction of hydrogen, in spite of the strong tendency of the particles to form aggregates. During the hydrogen evolution process, it does not loose its catalytic properties. It was confirmed that RuO 2 does not catalyze the hydrogenation of methylviologen. A disadvantage of RuO 2 is that it absorbs light throughout the entire visible region.Upon illumination of the reaction dispersion and after a certain induction time, hydrogen production takes place at a constant rate (steady state). After several hours, the production rate gradually decreases to zero. The maximum attainable amount of H 2 is determined by the initial amount of electron donor: each EDTA species can regenerate three oxidized sensitizer ions. However, in most experiments the total H 2 yield was less due to gradual destruction of methylviologen in the bulk solution.The steady state ratio [MV +.]/[MV 2+] appeared to be always low, even in the absence of catalyst. This must be the result of a yet unspecified reaction which reconverts MV +.into MV 2+. Probably, a photogenerated intermediate species is involved in this process.In all the experiments with the hydrogen photoproduction system, the incident light intensity was a rate-determining factor. The steady state rate of hydrogen production depends also, but to a lower extent, on the sensitizer concentration. It has been shown in a simple way that the first step in the hydrogen evolution process, i.e. the excitation of Ru(bipy)32+, is first order in the light intensity and less than first order in the sensitizer concentration.The hydrogen production rate increases with EDTA concentration up to a plateau above ca. 0.02 M. At the plateau, the oxidized sensitizer is regenerated efficiently, preventing back-reaction with MV + .As a function of methylviologen concentration, the production rate exhibits a maximum around 2 x 10 -3M.At low quantities of RuO 2 (< 10 mg), the available catalytic surface area is rate-limiting. At higher catalyst amounts, the production rate is fairly constant; it decreases slightly with increasing RuO 2 amount due to the absorption of light by the RuO 2 particles.For any amount of RuO 2 , the stirring rate affects the rate of hydrogen evolution. Mass transfer of H +to the catalyst surface is not rate-limiting, as is also confirmed by the insensitivity of the production rate to the buffer concentration. This implies that the mass transfer of MV + .to the catalyst surface is a rate-determining factor.Most of the abovementioned experimental results can be satisfactorily simulated using a quantitative model, in which the homogeneous reactions are described by steady state kinetic equations and the heterogeneous processes as electrode reactions. The catalytic properties of RuO 2 can be understood and predicted by considering the RuO 2 aggregates as microelectrodes. Probably, the electrical conductivity of RuO 2 -on the level of a metallic conductoris essential for its catalytic performance.Hydrogen evolution at the catalyst surface takes place near the equilibrium potential of the H +/H 2 couple. At these potentials, reconversion of MV 2+into MV + .at the catalyst surface is negligible. The rate of the heterogeneous processes is determined by the rate of mass transfer of MV + .to the surface and, to a lower degree, by the rate of interfacial electron transfer. The mass transfer coefficient of methylviologen, under the standard stirring conditions, appeared to be in the order of 10 -5m/s.Mass transfer of methylviologen would undoubtedly be favoured by a better dispersion of the catalyst, since aggregation of the RuO 2 particles makes the surface less accessible. If the same or higher hydrogen production rates could be reached with lower catalyst amounts, the disadvantage of light absorption by the RuO 2 particles would become less important. Therefore, it seems worth trying again to stabilize dispersions of RuO 2 , for example by covalently linking polymers to the oxide surface.The simulations further indicate that, if the total surface area of the RuO 2 particles is assumed to be catalytically active, the kinetic parameters i o and k oare only ca. 10 times lower than the corresponding values found for the RuO 2 film electrodes per unit geometrical surface area. This is surprising, because the roughness factor of these electrodes was estimated to be in the order of several hundreds. This point deserves further attention. Aspects that could be investigated, are the influence of heat treatments on the reductive catalytic properties of RuO 2 and the comparison with kinetic parameters for single crystal RuO 2 electrodes.The presented model for the hydrogen production system does not account for the maximum in hydrogen production rate as a function of methylviologen concentration. The differences between model predictions and experimental results point to a progressive inhibition of the heterogeneous processes with increasing MV 2+concentration. This aspect will be the subject of further study, including investigation of the dependency of the electron transfer rate constant on the bulk concentration of methylviologen.The overall quantum yield of the hydrogen production in our standard system is low; even with an excess of catalyst, it is less than 4 %. Since reconversion of MV 2+into MV + .at the catalyst surface does not take place (each MV + .species that reaches the surface is used for hydrogen production), the low efficiency of the system results from the homogeneous proceases. Reconversion of MV + .into MV 2+in solution is competitive with the production of hydrogen and makes the system less efficient. The quantum yield is also limited by the low efficiency of the quenching of the excited sensitizer by methylviologen. At pH 4.6, less than 25 % of the quenching acts results in charge separation (according to our numerical simulations ca. 16 %). Furthermore, the gradual destruction of methylviologen under illumination of the reaction mixture, makes this compound unsuitable for use in any practical device for photogeneration of hydrogen.Combination of information regarding the homogeneous and interfacial aspects of the hydrogen production system leads to a picture that is at least semiquantitatively, and in many aspects quantitatively consistent. Extentions of this approach could be useful for the rational design of catalytic systems for solar energy conversion