Burden of disease from exposure to secondhand smoke in children in Europe

BACKGROUND

Secondhand smoke (SHS) exposure at home and fetal SHS exposure during pregnancy are a major cause of disease among children. The aim of this study is quantifying the burden of disease due to SHS exposure in children and in pregnancy in 2006-2017 for the 28 European Union (EU) countries.

METHODS

Exposure to SHS was estimated using a multiple imputation procedure based on the Eurobarometer surveys, and SHS exposure burden was estimated with the comparative risk assessment method using meta-analytical relative risks. Data on deaths and disability-adjusted life years (DALYs) were collected from National statistics and from the Global Burden of Disease Study.

RESULTS

Exposure to SHS and its attributable burden stalled in 2006-2017; in pregnant women, SHS exposure was 19.8% in 2006, 19.1% in 2010, and 21.0% in 2017; in children it was 10.1% in 2006, 9.6% in 2010, and 12.1% in 2017. In 2017, 35,633 DALYs among children were attributable to SHS exposure in the EU, mainly due to low birth weight.

CONCLUSIONS

Comprehensive smoking bans up to 2010 contributed to reduce SHS exposure and its burden in children immediately after their implementation; however, SHS exposure still occurs, and in 2017, its burden in children was still relevant.

IMPACT

Exposure to secondhand smoke at home and in pregnancy is a major cause of disease among children. Smoking legislation produced the adoption of voluntary smoking bans in homes; however, secondhand smoke exposure at home still occurs and its burden is substantial. In 2017, the number of deaths and disability-adjusted life years in children attributable to exposure to secondhand smoke in the European Union countries were, respectively, 335 and 35,633. Low birth weight caused by secondhand smoke exposure in pregnancy showed the largest burden. Eastern European Union countries showed the highest burden.

Peptide model systems for amyloid fiber formation: design strategies and validation methods

The rational understanding of the factors involved in the formation of amyloid deposits in tissue is fundamental to the identification of novel therapeutic strategies to prevent or cure pathological conditions such as Alzheimer's and Parkinson's disease or spongiform encephalopathies. Given the complexity of the molecular events driving protein self-association, a frequent strategy in the field has consisted of designing simplified model systems that facilitate the analysis of the elements that predispose polypeptides toward amyloid formation. In fact, these systems have provided very valuable knowledge on the determinants underlying structural transitions to the polymeric beta-sheet state present in amyloid fibers and more disordered aggregates. In this chapter, we will describe different approaches to obtain and design model systems for amyloidogenesis, as well as the methodologies that are typically used to validate them. We will also show how some of the general principles obtained from these studies can be applied for de novo design purposes and for the sequence-based identification of amyloidogenic stretches in proteins.

Design of model systems for amyloid formation: lessons for prediction and inhibition

The determination of the physico-chemical principles underlying amyloid deposition is fundamental to the identification of therapeutic strategies to prevent or cure amyloid-related disorders. Given the complexity of the molecular events involved in protein self-association, researchers have designed simplified systems that facilitate the discovery of factors that predispose polypeptides to amyloid formation and aggregation. These systems have provided valuable knowledge about the determinants underlying the structural transitions to the polymeric beta-sheet state present in amyloid fibers and in more disordered aggregates. The integration of this knowledge is crucial to the identification of the regions responsible for the amyloidogenic and aggregating behavior of a given protein. The reliable discovery of amyloid-promoting fragments in proteins should have a great impact on the development of anti-amyloid agents. Also, methods that identify aggregation-prone motifs have a broad range of biotechnological applications, such as the improvement of the solubility of recombinant proteins for pharmaceutical and industrial purposes, and peptide-based biomaterial engineering.

Insights into the determinants of beta-sheet stability: 1H and 13C NMR conformational investigation of three-stranded antiparallel beta-sheet-forming peptides

In a previous study we designed a 20-residue peptide able to adopt a significant population of a three-stranded antiparallel beta-sheet in aqueous solution (de Alba et al. [1999]Protein Sci.8, 854-865). In order to better understand the factors contributing to beta-sheet folding and stability we designed and prepared nine variants of the parent peptide by substituting residues at selected positions in its strands. The ability of these peptides to form the target motif was assessed on the basis of NMR parameters, in particular NOE data and 13Calpha conformational shifts. The populations of the target beta-sheet motif were lower in the variants than in the parent peptide. Comparative analysis of the conformational behavior of the peptides showed that, as expected, strand residues with low intrinsic beta-sheet propensities greatly disfavor beta-sheet folding and that, as already found in other beta-sheet models, specific cross-strand side chain-side chain interactions contribute to beta-sheet stability. More interestingly, the performed analysis indicated that the destabilization effect of the unfavorable strand residues depends on their location at inner or edge strands, being larger at the latter. Moreover, in all the cases examined, favorable cross-strand side chain-side chain interactions were not strong enough to counterbalance the disfavoring effect of a poor beta-sheet-forming residue, such as Gly.

Salmonid viral haemorrhagic septicaemia virus: fusion-related enhancement of virus infectivity by peptides derived from viral glycoprotein G or a combinatorial library

To search for enhancers and/or inhibitors of viral haemorrhagic septicaemia virus (VHSV, a salmonid rhabdovirus) infectivity, a total of 51 peptides from a pepscan of viral envelope protein G, a recombinant peptide from protein G (frg11) and 80 peptide mixtures from an alpha-helix-favoured combinatorial library were screened. However, contrary to what occurs in many other enveloped viruses, only peptides enhancing rather than inhibiting VHSV infectivity were found. Because some of the enhancer pepscan G peptides and frg11 were derived from phospholipid-binding or fusion-related regions identified previously, it was suggested that enhancement of virus infectivity might be related to virus-cell fusion. Furthermore, enhancement was significant only when the viral peptides were pre-incubated with VHSV at the optimal low pH of fusion, before being adjusted to physiological pH and assayed for infectivity. Enhancement of VHSV infectivity caused by the pre-incubation of VHSV with peptide p5 (SAAEASAKATAEATAKG), one of the individual enhancer peptides defined from the screening of the combinatorial library, was independent of the pre-incubation pH. However, it was also related to fusion because the binding of p5 to protein G induced VHSV to bypass the endosome pathway of infection and reduced the low-pH threshold of fusion, thus suggesting an alternative virus entry pathway for p5-VHSV complexes. Further investigations into VHSV enhancer peptides might shed some light on the mechanisms of VHSV fusion.

Influence of the hydrophilic face on the folding ability and stability of alpha-helix bundles: relevance to the peptide catalytic activity

Although not the sole feature responsible, the packing of amino acid side chains in the interior of proteins is known to contribute to protein conformational specificity. While a number of amphipathic peptide sequences with optimized hydrophobic domains has been designed to fold into a desired aggregation state, the contribution of the amino acids located on the hydrophilic side of such peptides to the final packing has not been investigated thoroughly. A set of self-aggregating 18-mer peptides designed previously to adopt a high level of alpha-helical conformation in benign buffer is used here to evaluate the effect of the nature of the amino acids located on the hydrophilic face on the packing of a four alpha-helical bundle. These peptides differ from one another by only one to four amino acid mutations on the hydrophilic face of the helix and share the same hydrophobic core. The secondary and tertiary structures in the presence or absence of denaturants were determined by circular dichroism in the far- and near-UV regions, fluorescence and nuclear magnetic resonance spectroscopy. Significant differences in folding ability, as well as chemical and thermal stabilities, were found between the peptides studied. In particular, surface salt bridges may form which would increase both the stability and extent of the tertiary structure of the peptides. The structural behavior of the peptides may be related to their ability to catalyze the decarboxylation of oxaloacetate, with peptides that have a well-defined tertiary structure acting as true catalysts.

Novel, potent calmodulin antagonists derived from an all-D hexapeptide combinatorial library that inhibit in vivo cell proliferation: activity and structural characterization

Calmodulin is known to bind to various amphipathic helical peptide sequences, and the calmodulin-peptide binding surface has been shown to be remarkably tolerant sterically. D-Amino acid peptides, therefore, represent potential nonhydrolysable intracellular antagonists of calmodulin. In the present study, synthetic combinatorial libraries have been used to develop novel D-amino acid hexapeptide antagonists to calmodulin-regulated phosphodiesterase activity. Five hexapeptides were identified from a library containing over 52 million sequences. These peptides inhibited cell proliferation both in cell culture using normal rat kidney cells and by injection via the femoral vein following partial hepatectomy of rat liver cells. These hexapeptides showed no toxic effect on the cells. Despite their short length, the identified hexapeptides appear to adopt a partial helical conformation similar to other known calmodulin-binding peptides, as shown by CD spectroscopy in the presence of calmodulin and NMR spectroscopy in DMSO. The present peptides are the shortest peptide calmodulin antagonists reported to date showing potential in vivo activity.

Addressing substrate glutamine requirements for tissue transglutaminase using substance P analogues

We have investigated the effect on the substrate requirements for guinea pig liver (tissue) transglutaminase of a set of 11 synthetic glutamine substitution analogues making up the full sequence of the naturally occurring tissue transglutaminase substrate substance P. While a number of peptide sequences derived from proteins that are well-recognized as tissue transglutaminase substrates have been studied, the enzyme activity using substitution analogues of full-length natural substrates has not been investigated as thoroughly. Thus, our set of substance P analogues only differs from one to other by one amino acid mutation while the length (of the peptide) is maintained as in the natural parent peptide. Our results indicate that a glutamine residue is not recognized as substrate by the enzyme whether it is placed at the N- or C-terminal or between two positively charged residues or between two proline residues. To further address the effect on enzyme activity of charged amino acids in the vicinity of the reactive glutamine residue, a new set of synthetic charge replacement analogues of substance P has been also studied. Together, the results have identified new minimal requirements for modification of a particular glutamine residue in a polypeptide chain. It would be of interest to set up a full set of such requirements in order to highlight potential glutamine residues as enzyme targets in the growing list of proteins that are being described as transglutaminase substrates.