Electroactive Amphiphiles for Addressable Supramolecular Nanostructures

In this focus review we aim to highlight an exciting class of materials, electroactive amphiphiles (EAAs). This class of functional amphiphilic molecules has been the subject of sporadic investigations over the last few decades, but little attempt has been made to date to gather or organise these investigations into a logical fashion. Here we attempted to gather the most important contributions, provide a framework in which to discuss them, and, more importantly, point towards the areas where we believe these EAAs will contribute to solving wider scientific problems and open new opportunities. Our discussions cover materials based on low molecular weight ferrocenes, viologens and anilines, as well as examples of polymeric and supramolecular EAAs. With the advances of modern analytical techniques and new tools for modelling and understanding optoelectronic properties, we believe that this area of research is ready for further exploration and exploitation.

Complex three-dimensional self-assembly in proxies for atmospheric aerosols

Aerosols are significant to the Earth’s climate, with nearly all atmospheric aerosols containing organic compounds that often contain both hydrophilic and hydrophobic parts. However, the nature of how these compounds are arranged within an aerosol droplet remains unknown. Here we demonstrate that fatty acids in proxies for atmospheric aerosols self-assemble into highly ordered three-dimensional nanostructures that may have implications for environmentally important processes. Acoustically trapped droplets of oleic acid/sodium oleate mixtures in sodium chloride solution are analysed by simultaneous synchrotron small-angle X-ray scattering and Raman spectroscopy in a controlled gas-phase environment. We demonstrate that the droplets contained crystal-like lyotropic phases including hexagonal and cubic close-packed arrangements of spherical and cylindrical micelles, and stacks of bilayers, whose structures responded to atmospherically relevant humidity changes and chemical reactions. Further experiments show that self-assembly reduces the rate of the reaction of the fatty acid with ozone, and that lyotropic-phase formation also occurs in more complex mixtures more closely resembling compositions of atmospheric aerosols. We suggest that lyotropic-phase formation likely occurs in the atmosphere, with potential implications for radiative forcing, residence times and other aerosol characteristics.

Nearly all atmospheric aerosols contain surface-active organic compounds; however, the nature of how they arrange remains poorly understood. Here, the authors show that fatty acids in atmospheric aerosol proxies self-assemble into highly ordered, viscous 3D nanostructures that undergo changes upon exposure to humidity and ozone.

Lactobacillus fermentum 3872 as a potential tool for combatting Campylobacter jejuni infections

Due to the global spread of multidrug resistant pathogenic bacteria, alternative approaches in combating infectious diseases are required. One such approach is the use of probiotics. Lactobacillus fermentum 3872 is a promising probiotic bacterium producing a range of antimicrobial compounds, such as hydrogen peroxide and lactic acid. In addition, previous studies involving genome sequencing and analysis of L. fermentum 3872 allowed the identification of a gene encoding a cell surface protein referred to as collagen binding protein (CBP) (not found in other strains of the species, according to the GenBank database), consisting of a C-terminal cell wall anchor domain (LPXT), multiple repeats of ‘B domains' that form stalks presenting an “A domain” required for adhesion. In this study, we found that the CBP of L. fermentum 3872 binds to collagen I present on the surface of the epithelial cells lining the gastrointestinal tract. Moreover, we found that this host receptor is also used for attachment by the major gastrointestinal pathogen, Campylobacter jejuni. Furthermore, we identified an adhesin involved in such interaction and demonstrated that both L. fermentum 3872 and its CBP can inhibit binding of this pathogen to collagen I. Combined with the observation that C. jejuni growth is affected in the acidic environment produced by L. fermentum 3872, the finding provides a good basis for further investigation of this strain as a potential tool for fighting Campylobacter infections.

Ultra-fast stem cell labelling using cationised magnetoferritin

Magnetic cell labelling with superparamagnetic iron oxide nanoparticles (SPIONs) facilitates many important biotechnological applications, such as cell imaging and remote manipulation. However, to achieve adequate cellular loading of SPIONs, long incubation times (24 hours and more) or laborious surface functionalisation are often employed, which can adversely affect cell function. Here, we demonstrate that chemical cationisation of magnetoferritin produces a highly membrane-active nanoparticle that can magnetise human mesenchymal stem cells (hMSCs) using incubation times as short as one minute. Magnetisation persisted for several weeks in culture and provided significant T2* contrast enhancement during magnetic resonance imaging. Exposure to cationised magnetoferritin did not adversely affect the membrane integrity, proliferation and multi-lineage differentiation capacity of hMSCs, which provides the first detailed evidence for the biocompatibility of magnetoferritin. The combination of synthetic ease and flexibility, the rapidity of labelling and absence of cytotoxicity make this novel nanoparticle system an easily accessible and versatile platform for a range of cell-based therapies in regenerative medicine.

Lactobacillus fermentum 3872 genome sequencing reveals plasmid and chromosomal genes potentially involved in a probiotic activity

In this report we describe a Lactobacillus fermentum 3872 plasmid (pLF3872) not previously found in any other strain of this species. The analysis of the complete sequence of this plasmid revealed the presence of a gene encoding a large collagen-binding protein (CBP), as well as the genes responsible for plasmid maintenance and conjugation. Potential roles of CBP and a chromosomally encoded fibronectin-binding protein (FbpA) in probiotic activity are discussed.

Immunohistochemical discrimination of wild-type EGFR from EGFRvIII in fixed tumour specimens using anti-EGFR mAbs ICR9 and ICR10

Background:

The human epidermal growth factor receptor (EGFR) is an important therapeutic target in oncology, and three different types of EGFR inhibitors have been approved for the treatment of cancer patients. However, there has been no clear association between the expression levels of EGFR protein in the tumours determined by the FDA-approved EGFR PharmDx kit (Dako) or other standard anti-EGFR antibodies and the response to the EGFR inhibitors.

Method:

In this study, we investigated the potential of our anti-EGFR monoclonal antibodies (mAbs; ICR9, ICR10, ICR16) for immunohistochemical diagnosis of wild-type EGFR and/or the type-III deletion mutant form of EGFR (EGFRvIII) in formalin-fixed, paraffin-embedded human tumour specimens.

Results:

We found that the anti-EGFR mAb in the EGFR PharmDx kit stained both wild-type and EGFRvIII-expressing cells in formalin-fixed, paraffin-embedded sections. This pattern of EGFR immunostaining was also found with our anti-EGFR mAb ICR16. In contrast, mAbs ICR10 and ICR9 were specific for the wild-type EGFR.

Conclusion:

We conclude that mAbs ICR9 and ICR10 are ideal tools for investigating the expression patterns of wild-type EGFR protein in tumour specimens using immunohistochemistry, and to determine their prognostic significance, as well as predictive value for response to therapy with EGFR antibodies.

Anti-tumour activity of afatinib, an irreversible ErbB family blocker, in human pancreatic tumour cells

BACKGROUND

The combination of the reversible epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI) erlotinib with gemcitabine obtained FDA approval for treating patients with pancreatic cancer. However, duration of response is often limited and there is currently no reliable predictive marker.

METHODS

We determined the sensitivity of a panel of human pancreatic tumour cell lines to treatment with afatinib, erlotinib, monoclonal antibody (mAb) ICR62, and gemcitabine, using the Sulforhodamine B colorimetric assay. The effect of these agents on cell signalling and cell-cycle distribution was determined by western blot and flow cytometry, respectively.

RESULTS

At 200 nM, ICR62 had no effect on growth of these tumour cells with the exception of BxPC-3 cells. BxPC-3 cells were also sensitive to treatment with afatinib and erlotinib with respective IC(50) values of 11 and 1200 nM. Compared with erlotinib, afatinib was also more effective in inhibiting the growth of the other human pancreatic tumour cell lines and in blocking the EGF-induced phosphorylation of tyrosine, EGFR, MAPK, and AKT. When tested in BxPC-3 xenografts, afatinib induced significant delay in tumour growth.

CONCLUSION

The superiority of afatinib in this study encourages further investigation on the therapeutic potential of afatinib as a single agent or in combination with gemcitabine in pancreatic cancer.

A family of polynuclear cobalt and nickel complexes stabilised by 2-pyridonate and carboxylate ligands

The synthesis and structural characterisation of a series of cobalt and nickel cages are reported. Eight of these structures contain a [M10(mu3-OH)6(eta2, mu3-xhp),(eta2, mu2-O2CR)6]2+ core (where M = Co or Ni; xhp = 6-chloro- or 6-methyl-2-pyridonate: R = Me, Ph, CHMe2, CH2Cl, CHPh2 or CMe3), where the ten metal atoms describe a centred-tricapped-trigonal prism (ttp). The cage contains six hydroxide ligands around the central metal, and the exterior is coated with pyridonate and carboxylate ligands. For four of the cages additional metal centres are found attached to the upper and/or lower triangular faces of the trigonal prism, generating dodeca- and undecanuclear cages. Three further cages are reported that contain a metal core based on an incomplete centred-tetraicosahedron. These cages involve trimethylacetate as a ligand in company with either 6-methyl-2-pyridonate or 6-chloro-2-pyridonate. Comparison of these latter structures with the trigonal prisms reveal that they can be described as a pentacapped-trigonal prism missing one edge. Magnetic studies of three of the nickel cages with trigonal prismatic cores show spin ground states of S = 8, 4 and 2 for Ni12, Ni11 and Ni10 cages, respectively.

The effect of platelet inhibitory therapy on graft thromboresistance

Greyhounds (n = 38) were randomized to aspirin and dipyridamole (ASA + DPM), the thromboxane synthetase inhibitor (TSI) CGS12970 (CIBA-GEIGY) or placebo twice daily for 48 hours prior to bilateral implantation of femoral artery Dacron grafts. In-vivo 111In-platelet deposition on grafts was measured at 5 days and 2 months. Grafts were removed at 2 months when ex-vivo graft and arterial release of 6-ketoprostaglandin F1a (6-keto PGF1a) was measured by radioimmunoassay. Graft 6-keto-PGF1a was significantly increased by CGS12970 but ASA + DPM had no significant effect. ASA + DPM significantly reduced arterial 6-keto-PGF1a although this was marginally increased by CGS12970. Neither active treatment reduced in-vivo 111In-platelet deposition. Preservation of vascular or graft prostacyclin by thromboxane synthetase inhibitors may represent an alternative strategy in preventing prosthetic graft thrombosis.

Popliteal artery aneurysm. Prompt intervention prevents tragic consequences

Popliteal artery aneurysm is an important, if uncommon, cause of lower extremity ischemia. About half of cases are asymptomatic. Untreated aneurysms may lead to embolization, rupture, thrombosis, and amputation. Diagnosis involves careful physical examination and use of ultrasound and arteriography. Prompt surgical intervention is essential.

Mesothelial seeding of knitted Dacron

Bilateral superficial femoral artery replacement using knitted Dacron was performed in 38 dogs. One side was seeded with omental mesothelium and the other acted as an unseeded control. 111In-labelled platelet accumulation on grafts was measured at 5 days and 2 months and the thrombogenicity index of seeded and unseeded grafts calculated. Patency was monitored for 2 months, at which time grafts were removed and luminal thrombus, ultrastructural cell cover and prostacyclin release were measured. Cell seeding did not influence the mean(s.e.m.) thrombogenicity index of 0.95(0.25) and 0.88(0.24) at 5 days in control and seeded grafts respectively; nor was there any difference between the groups at 2 months. Occlusion occurred in six control and four seeded grafts. Seeding did not significantly improve the percentage thrombus-free area or luminal cell cover. Neither did it enhance mean(s.e.m.) luminal 6-keto-prostaglandin F1 alpha release of 2.58(0.80) pg cm-2 in controls and 2.63(0.78) pg cm-2 in seeded grafts. Further studies demonstrated that only a mean(s.e.m.) of 4.4(1.9) per cent of the seeded inoculum was present on grafts 48 h after implantation, providing too few cells to achieve confluent cover. Mesothelial cell seeding might be useful in promoting a healed graft surface but critical levels of seeding density must be achieved before the technique can be properly evaluated.

The effect of platelet inhibitory therapy on prosthetic graft maturation

Thirty-eight dogs were randomized to the thromboxane synthetase inhibitor CGS12790 (3 mg/kg), aspirin 150 mg and dipyridamole 50 mg (ASA + DPM) or placebo (PLA), all twice daily. Two days later, animals underwent bilateral superficial femoral artery replacement with knitted Dacron. Grafts were removed at two months and subjected to macroscopic and histological examination. Thirty dogs survived to two months. Percentage thrombus free area (TFA) was increased from 15.1 +/- 2.2 with PLA to 46.6 +/- 5.2 with CGS12970 (P < 0.001) and to 32.9 +/- 5.0 with ASA + DPM (P < 0.01). At the anastomoses, only CGS12970 significantly reduced neointimal thickness, promoted pannus ingrowth and improved endothelialization. Percentage luminal occlusion at the midgraft was reduced from 48.2 +/- 5.9 with PLA to 33.9 +/- 2.7 with CGS12970 (P < 0.05). These results provide further evidence that platelet inhibitory therapy reduces thrombosis but also that the platelet is involved in anastomotic maturation. Therapy directed against thromboxane synthesis has potential that may be useful in clinical practice.

An immunohistochemical study of mesothelial cell seeding for knitted Dacron

Six greyhounds underwent bilateral femoral artery replacement with knitted Dacron, one side seeded with omental digest at graft preclotting, the other acting as an unseeded control. Grafts were removed at 24 hours and two months. Tissue was examined using a monoclonal antibody (MNF116) directed against a broad range of human cytokeratins to differentiate mesothelial cells (MC) from microvascular endothelial cells (MEC), which stained only with a polyclonal antibody directed against von Willebrand Factor (anti-vWF). Cells released from omentum by collagenase stained with MNF116 and reacted poorly with anti-vWF. Identical cells were observed to be within the interstices of seeded but not control knitted Dacron. Few remained in seeded grafts (n = 2) removed at 24 hours and none at two months (n = 4).

Primary prevention of atherosclerosis by lovastatin in a genetically hyperlipidaemic rabbit strain

Lovastatin, a lipid-lowering drug which inhibits cholesterol synthesis, was administered to genetically hyperlipidaemic rabbits from the age of 2 months. Twenty rabbits were selected with similar plasma cholesterol levels and divided into matched treatment and control groups. The treated animals showed a 60% decrease in plasma cholesterol due to reduced levels of low density lipoprotein (LDL) and intermediate density lipoprotein (IDL). Levels of other lipoproteins remained unchanged. In untreated animals cholesterol levels in plasma, LDL and IDL increased with age. The area of aortic atherosclerosis-like lesions was quantified after 2-10.5 months of treatment. At each time point the extent of arterial disease was profoundly less in treated than in untreated animals. The findings demonstrate that primary prevention of arterial lesions resembling human atherosclerosis (increased amounts of fibrous tissue, smooth muscle cell proliferation, foam cell formation and necrosis at the base of the plaques) results from early effective reduction of elevated plasma lipids by lovastatin in this rabbit strain.

A new treatment for urethral strictures

A urethral stent, originally developed for endovascular use, was implanted into eight patients with urethral strictures after experimental studies in the canine urethra. The stent is woven in the form of a tubular mesh from surgical grade stainless steel wire and is self-expanding when released from its small-diameter delivery catheter. At follow-up 6 months to 1 year postoperatively (mean 8 months) all had a good calibre urethra. Urethroscopy showed complete epithelial covering of the implant at 4-6 months.

Biliary stent blockage with bacterial biofilm. A light and electron microscopy study

Clogging of endoscopic stents necessitates their replacement in many patients with malignant obstructive jaundice and limits their use in benign strictures. We studied the basic mechanism of clogging to find ways to prevent it. We did light and electron microscopy studies of blocked and functioning stents, which were prepared so that organic structures would be preserved. The material blocking the lumina was composed of a matrix of bacterial cells and their fibrillar anionic extracellular products. Crystals of calcium bilirubinate, calcium palmitate, and cholesterol were embedded within this matrix. Bacterial cells were attached to the stent surface by a fibrillar matrix, suggesting that the initial event in stent clogging is the development of an adherent bacterial biofilm. Bacterial enzyme activity (beta-glucuronidase and phospholipase) leads to the deposition of crystals. The use of antibacterial plastics in the manufacture of stents may reduce bacterial adhesion and stent clogging.

Hereditary hyperlipidemia and atherosclerosis in the rabbit due to overproduction of lipoproteins. II. Preliminary report of arterial pathology

A genetically determined hyperlipidemic strain of New Zealand White rabbit that has features in common with combined familial hyperlipidemia in humans has been identified. The morphologic findings in a few animals fed a normal chow diet are reported. These consisted of macroscopically visible aortic intimal elevations found in the greatest number in the descending thoracic aorta. The plaques showed the presence of a cell population consisting of modified smooth muscle cells and lipid-laden macrophages. The lesion bases were necrotic and acellular, and some showed the presence of dystrophic calcification. Scanning electron microscopy revealed numerous monocytes attached to the endothelium. Endothelial defects were common, and these were filled with swollen and "ruffled" macrophages. Transmission electron microscopy confirmed the presence of lipid-laden cells penetrating between adjacent endothelial cells. These findings resemble those reported in a number of different animal species after dietary induction of hyperlipidemia. This strain is a useful new model for the study of atherogenesis.