Oestrogen-mediated cardioprotection following ischaemia and reperfusion is mimicked by an oestrogen receptor (ER)α agonist and unaffected by an ERβ antagonist

Oestrogen protects the heart from ischaemic injury. The current study aims to characterise two novel oestrogen receptor (ER) ligands, an ERα agonist ERA-45 and an ERβ antagonist ERB-88, and then use them to investigate the roles of ERα and ERβ in mediating the cardioprotection by E from ischaemia–reperfusion injury in the rat. The ER ligands were characterised by gene transactivation assay using ER-transfected Chinese hamster ovary (CHO) cells and in bioavailability studies in vivo. Female rats (n=48) were ovariectomised and implanted with 17β-oestradiol (17βE2) releasing or placebo pellets. ERA-45, ERB-88 or vehicle was administered for 5 days prior to ischaemia–reperfusion studies. Necrosis, neutrophil infiltration (myeloperoxidase activity) and oxidant stress production (electron paramagnetic resonance) from the area-at-risk were measured to assess reperfusion injury. The ERα agonist ERA-45 showed more than 35-fold selectivity for ERα compared with ERβ gene transactivation. In vitro, the ERβ antagonist ERB-88 inhibited transactivation by 17βE2 via ERβ with 46-fold selectivity relative to inhibition via ERα. In vivo, 17βE2 significantly reduced neutrophil infiltration, oxidant stress and necrosis following ischaemia and reperfusion. Cardioprotection by 17βE2 was not inhibited by ERB-88 but was completely reproduced by ERA-45. In conclusion, protection of the rat heart after ischaemia–reperfusion by 17βE2 is achieved through the reduction of cardiomyocyte death, neutrophil infiltration and oxygen-free radical availability.The results of this study indicate that these effects are primarily mediated via activation of ERα

The use of tyrosinases in a chemoenzymatic cascade as a peptide ligation strategy

Peptides play many key roles in biological systems and numerous methods have been developed to generate both natural and unnatural peptides. However, straightforward, reliable coupling methods that can be achieved under mild reactions conditions are still sought after. In this work, a new N-terminal tyrosine-containing peptide ligation method with aldehydes, utilising a Pictet–Spengler reaction is described. In a key step, tyrosinase enzymes have been used to convert L-tyrosine to L-3,4-dihydroxyphenyl alanine (L-DOPA) residues, generating suitable functionality for the Pictet–Spengler coupling. This new chemoenzymatic coupling strategy can be used for fluorescent-tagging and peptide ligation purposes

Understanding and optimising the transfection of lipopolyplexes formulated in saline: the effects of peptide and serum

Lipopolyplexes (LPDs) are of considerable interest for use as gene delivery vehicles. Here LPDs have been prepared from cationic vesicles (composed of a 1 : 1 molar ratio of DOTMA with the neutral helper lipid, DOPE), singly branched cationic peptides and plasmid DNA. All peptides contained a linker sequence (cleaved by endosomal furin) attached to a targeting sequence selected to bind human airway epithelial cells and mediate gene delivery. The current study investigates the effects of novel Arg-containing cationic peptide sequences on the biophysical and transfection properties of LPDs. Mixed His/Arg cationic peptides were of particular interest, as these sequences have not been previously used in LPD formulations. Lengthening the number of cationic residues in a homopolymer from 6 to 12 in each branch reduced transfection using LPDs, most likely due to increased DNA compaction hindering the release of pDNA within the target cell. Furthermore, LPDs containing mixed Arg-containing peptides, particularly an alternating Arg/His sequence exhibited an increase in transfection, probably because of their optimal ability to complex and subsequently release pDNA. To confer stability in serum, LPDs were prepared in 0.12 M sodium chloride solution (as opposed to the more commonly used water) yielding multilamellar LPDs with very high levels of size reproducibility and DNA protection, especially when compared to the (unilamellar) LPDs formed in water. Significantly for the clinical applications of the LPDs, those prepared in the presence of sodium chloride retained high levels of transfection in the presence of media supplemented with fetal bovine serum. This work therefore represents a significant advance for the optimisation of LPD formulation for gene delivery, under physiologically relevant conditions, in vivo

<i>Campylobacter jejuni</i> HS:23 and Guillain-Barré Syndrome, Bangladesh

To the Editor: Guillain-Barré syndrome (GBS) is an acute peripheral neuropathy triggered by a preceding infectious illness. Gastroenteritis caused by Campylobacter jejuni is the most frequently reported antecedent event. In Japan, South Africa, China, and Mexico, Campylobacter strains with certain Penner heat-stable (HS) serotypes, including HS:19 and HS:41, are overrepresented among isolates from GBS case-patients, compared with isolates from enteritis case-patients. Several studies indicate that C. jejuni HS:19 and HS:41 have a clonal population structure and suggest that these serotypes might have unique virulence properties that are intricately linked to development of GBS. However, data from the United Kingdom and the Netherlands suggest that such virulence properties may not be restricted to specific HS serotypes because many other serotypes can be cultured from patients with GBS (5). We report a non-HS:19 and non-HS:41 C. jejuni serotype and sequence type (ST)–3219 that are overrepresented among isolates from GBS patients in Bangladesh. [...

<i>Campylobacter jejuni</i> HS:23 and Guillain-Barré Syndrome, Bangladesh

To the Editor: Guillain-Barré syndrome (GBS) is an acute peripheral neuropathy triggered by a preceding infectious illness. Gastroenteritis caused by Campylobacter jejuni is the most frequently reported antecedent event. In Japan, South Africa, China, and Mexico, Campylobacter strains with certain Penner heat-stable (HS) serotypes, including HS:19 and HS:41, are overrepresented among isolates from GBS case-patients, compared with isolates from enteritis case-patients. Several studies indicate that C. jejuni HS:19 and HS:41 have a clonal population structure and suggest that these serotypes might have unique virulence properties that are intricately linked to development of GBS. However, data from the United Kingdom and the Netherlands suggest that such virulence properties may not be restricted to specific HS serotypes because many other serotypes can be cultured from patients with GBS (5). We report a non-HS:19 and non-HS:41 C. jejuni serotype and sequence type (ST)–3219 that are overrepresented among isolates from GBS patients in Bangladesh. [...

EGFR-targeted semiconducting polymer nanoparticles for photoacoustic imaging

Semiconducting polymer nanoparticles (SPN), formulated from organic semiconducting polymers and lipids, show promise as exogenous contrast agents for photoacoustic imaging (PAI). To fully realise the potential of this class of nanoparticles for imaging and therapeutic applications, a broad range of active targeting strategies, where ligands specific to receptors on the target cells are displayed on the SPN surface, are urgently needed. In addition, effective strategies for quantifying the level of surface modification are also needed to support development of ligand-targeted SPN. In this paper, we have developed methods to prepare SPN bearing peptides targeted to Epidermal Growth Factor Receptors (EGFR), which are overexpressed at the surface of a wide variety of cancer cell types. In addition to fully characterising these targeted nanoparticles by standard methods (UV–visible, photoacoustic absorption, dynamic light scattering, zeta potential and SEM), we have developed a powerful new NMR method to determine the degree of conjugation and the number of targeting peptides attached to the SPN. Preliminary in vitro experiments with the colorectal cancer cell line LIM1215 indicated that the EGFR-targeting peptide conjugated SPN were either ineffective in delivering the SPN to the cells, or that the targeting peptide itself destabilised the formulation. This in reinforces the need for effective characterisation techniques to measure the surface accessibility of targeting ligands attached to nanoparticles

EGFR-targeted semiconducting polymer nanoparticles for photoacoustic imaging

Semiconducting polymer nanoparticles (SPN), formulated from organic semiconducting polymers and lipids, show promise as exogenous contrast agents for photoacoustic imaging (PAI). To fully realise the potential of this class of nanoparticles for imaging and therapeutic applications, a broad range of active targeting strategies, where ligands specific to receptors on the target cells are displayed on the SPN surface, are urgently needed. In addition, effective strategies for quantifying the level of surface modification are also needed to support development of ligand-targeted SPN. In this paper, we have developed methods to prepare SPN bearing peptides targeted to Epidermal Growth Factor Receptors (EGFR), which are overexpressed at the surface of a wide variety of cancer cell types. In addition to fully characterising these targeted nanoparticles by standard methods (UV-visible, photoacoustic absorption, dynamic light scattering, zeta potential and SEM), we have developed a powerful new NMR method to determine the degree of conjugation and the number of targeting peptides attached to the SPN. Preliminary in vitro experiments with the colorectal cancer cell line LIM1215 indicated that the EGFR-targeting peptide conjugated SPN were either ineffective in delivering the SPN to the cells, or that the targeting peptide itself destabilised the formulation. This in reinforces the need for effective characterisation techniques to measure the surface accessibility of targeting ligands attached to nanoparticles

Tunable Semiconducting Polymer Nanoparticles with INDT-Based Conjugated Polymers for Photoacoustic Molecular Imaging.

Photoacoustic imaging combines both excellent spatial resolution with high contrast and specificity, without the need for patients to be exposed to ionizing radiation. This makes it ideal for the study of physiological changes occurring during tumorigenesis and cardiovascular disease. In order to fully exploit the potential of this technique, new exogenous contrast agents with strong absorbance in the near-infrared range, good stability and biocompatibility, are required. In this paper, we report the formulation and characterization of a novel series of endogenous contrast agents for photoacoustic imaging in vivo. These contrast agents are based on a recently reported series of indigoid π-conjugated organic semiconductors, coformulated with 1,2-dipalmitoyl-sn-glycero-3-phosphocholine, to give semiconducting polymer nanoparticles of about 150 nm diameter. These nanoparticles exhibited excellent absorption in the near-infrared region, with good photoacoustic signal generation efficiencies, high photostability, and extinction coefficients of up to three times higher than those previously reported. The absorption maximum is conveniently located in the spectral region of low absorption of chromophores within human tissue. Using the most promising semiconducting polymer nanoparticle, we have demonstrated wavelength-dependent differential contrast between vasculature and the nanoparticles, which can be used to unambiguously discriminate the presence of the contrast agent in vivo