Self-assembly and surface behaviour of pure and mixed zwitterionic amphiphiles in a deep eutectic solvent.

Recent investigations have shown that deep eutectic solvents provide a suitable environment for self-organisation of biomolecules, in particular phospholipids and proteins. However, the solvation of complex lyophilic moieties by deep eutectic solvents still remains unclear. Here we explore the behaviour of zwitterionic surfactants in choline chloride:glycerol eutectic mixture. Dodecyl-2-(trimethylammonio)ethylphosphate and N-alkyl-N,N-dimethyl-3-ammonio-1-propanesulfonate (alkyl = dodecyl, tetradecyl) surfactants were investigated by means of surface tension, X-ray reflectivity and small-angle neutron scattering. These surfactants were found to remain surface active and form globular micelles in deep eutectic solvents. Still, the surface behaviour of these species was found to differ depending on the headgroup and tail structure. The morphology of the micelles also slightly varies between surfactants, demonstrating differences in the packing of individual monomers. The characteristics of mixtures of the dodecyl surfactants is also reported, showing a deviation from ideal mixing associated with attractive interactions between sulfobetaine and phosphocholine headgroups. Such non-ideality results in variation of the surface behaviour and self-assembly of these surfactant mixtures. The results presented here will potentially lead to the development of new alternatives for drug-delivery, protein solubilisation and biosensing through a better fundamental understanding of the behaviour of zwitterionic surfactants in deep eutectic solvents.

Correlation between physical structure and magnetic anisotropy of a magnetic nanoparticle colloid.

We show the effects of a time-invariant magnetic field on the physical structure and magnetic properties of a colloid comprising 44 nm diameter magnetite magnetic nanoparticles, with a 24 nm dextran shell, in water. Structural ordering in this colloid parallel to the magnetic field occurs simultaneously with the onset of a colloidal uniaxial anisotropy. Further increases in the applied magnetic field cause the nanoparticles to order perpendicular to the field, producing unexpected colloidal unidirectional and trigonal anisotropies. This magnetic behavior is distinct from the cubic magnetocrystalline anisotropy of the magnetite and has its origins in the magnetic interactions among the mobile nanoparticles within the colloid. Specifically, these field-induced anisotropies and colloidal rearrangements result from the delicate balance between the magnetostatic and steric forces between magnetic nanoparticles. These magnetic and structural rearrangements are anticipated to influence applications that rely upon time-dependent relaxation of the magnetic colloids and fluid viscosity, such as magnetic hyperthermia and shock absorption.

Counterion binding alters surfactant self-assembly in deep eutectic solvents.

Micellisation of surfactants in deep eutectic solvents has been recently demonstrated to provide a controllable way to modify micelle morphology. Ion-pair interactions between the solvent and the surfactant headgroup were identified as affecting the micellisation by modifying the charge density of the micelle. Here we explore the micellisation of dodecylsulfate surfactants with different counterions (Li+, Cs+, Mg2+, Bmim+, Emim+, cholinium+) dissolved in two deep eutectic solvents: choline chloride:urea and choline chloride:glycerol. Surface tension results show a solvent and counterion dependence of the CMC of the surfactants. Small-angle neutron scattering was subsequently used to investigate the morphology of the micelles formed. The results show that the elongation of the micelles is strongly dependent on the solvent, showing more elongated aggregates in choline chloride:urea than in choline chloride:glycerol. The morphology of micelles in DES was also found to depend on the counterion, where the affinity of binding showed similarities to that in water.

Protein conformation in pure and hydrated deep eutectic solvents.

Deep eutectic solvents (DES) have recently been postulated as possible environments where protein structure may be preserved in the absence of water. Here we present our results towards understanding protein conformation in choline chloride-based DES and mixtures with water. Lysozyme and bovine serum albumin have been investigated by means of circular dichroism and small-angle neutron scattering.

Micelle structure in a deep eutectic solvent: a small-angle scattering study.

In recent years many studies into green solvents have been undertaken and deep eutectic solvents (DES) have emerged as sustainable and green alternatives to conventional solvents since they may be formed from cheap non-toxic organic precursors. In this study we examine amphiphile behaviour in these novel media to test our understanding of amphiphile self-assembly within environments that have an intermediate polarity between polar and non-polar extremes. We have built on our recently published results to present a more detailed structural characterisation of micelles of sodium dodecylsulfate (SDS) within the eutectic mixture of choline chloride and urea. Here we show that SDS adopts an unusual cylindrical aggregate morphology, unlike that seen in water and other polar solvents. A new morphology transition to shorter aggregates was found with increasing concentration. The self-assembly of SDS was also investigated in the presence of water; which promotes the formation of shorter aggregates.

Resonant Raman scattering of ZnSxSe1-x solid solutions: the role of S and Se electronic states.

A comprehensive Raman resonance scattering study of ZnSxSe1-x (ZnSSe) solid solutions over the whole compositional range (0 ≤ x ≤ 1) has been carried out using 325 and 455 nm excitation wavelengths. The Raman scattering intensities of LO ZnS-like and ZnSe-like phonon modes, corresponding to pure S and Se vibrations, respectively, are revealed to be significantly enhanced when excited with 325 nm excitation in the case of S vibrations, and with 455 nm in the case of Se vibrations. This behavior is explained by the interaction of the excitation photons with the corresponding S or Se electronic states in the conduction band, and further confirmed by first principles simulations. These findings advance the fundamental understanding of the coupling between the electronic transitions and photons in the case of Raman resonance effects, and provide inputs for further studies of lattice dynamics, especially in the case of chalcogenide materials. Additionally, the coexistence of modes corresponding to only S vibrations and only Se vibrations in the ZnSSe alloys makes these results applicable for the compositional assessment of ZnSSe compounds.

Surfactant Behavior of Sodium Dodecylsulfate in Deep Eutectic Solvent Choline Chloride/Urea.

Deep eutectic solvents (DES) resemble ionic liquids but are formed from an ionic mixture instead of being a single ionic compound. Here we present some results that demonstrate that surfactant sodium dodecyl sulfate (SDS) remains surface-active and shows self-assembly phenomena in the most commonly studied DES, choline chloride/urea. X-ray reflectivity (XRR) and small angle neutron scattering (SANS) suggest that the behavior is significantly different from that in water. Our SANS data supports our determination of the critical micelle concentration using surface-tension measurements and suggests that the micelles formed in DES do not have the same shape and size as those seen in water. Reflectivity measurements have also demonstrated that the surfactants remain surface-active below this concentration.

Global fishmeal and fish-oil supply: inputs, outputs and markets.

Recent data on fishmeal and fish-oil supply are presented identifying key producer countries and raw material sources and distinguishing between whole fish and by-products. The conversion of these raw materials into marine ingredients is discussed and global volumes presented. This is followed by a summary of the main countries using these marine ingredients over recent years. Uses of fishmeal and fish-oil by market segment are then presented. From this, a global mass balance of inputs and outputs is derived which allows the calculation of the input-to-output ratios (fish in:fish out; FIFO) for the main aquaculture production types to be made. Current areas of focus by the industry include the need to demonstrate sustainable practice, more strategic use of marine ingredients, greater use of fishery and land-animal by-products as well as vegetable substitutes, and novel sources of essential omega-3 fats, notably the long-chain polyunsaturated fatty acids, eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids. Implications are drawn for future supply prospects of fishmeal and fish-oil and their future role in aquaculture, agriculture and human health.

Nearly complete regression of tumors via collective behavior of magnetic nanoparticles in hyperthermia.

One potential cancer treatment selectively deposits heat to the tumor through activation of magnetic nanoparticles inside the tumor. This can damage or kill the cancer cells without harming the surrounding healthy tissue. The properties assumed to be most important for this heat generation (saturation magnetization, amplitude and frequency of external magnetic field) originate from theoretical models that assume non-interacting nanoparticles. Although these factors certainly contribute, the fundamental assumption of 'no interaction' is flawed and consequently fails to anticipate their interactions with biological systems and the resulting heat deposition. Experimental evidence demonstrates that for interacting magnetite nanoparticles, determined by their spacing and anisotropy, the resulting collective behavior in the kilohertz frequency regime generates significant heat, leading to nearly complete regression of aggressive mammary tumors in mice.

In-school eyecare in special education settings has measurable benefits for children's vision and behaviour.

OBJECTIVES: To determine whether implementation of comprehensive in-school eyecare results in measurable benefits for children and young people in terms of visual status, classroom behaviours and how well their visual needs are met. DESIGN: School-based observational study. PARTICIPANTS & METHODS: 200 pupils [mean age 10 years 9 months, 70% male, majority moderate (40%) or severe (35%) learning difficulty] of a special education school in the UK. A sector-agreed in-school eyecare framework including full eye examination and cycloplegic refraction, dispensing of spectacles (as appropriate) and written reporting of outcomes to parents/teachers was applied. Classroom behaviours were observed and recorded prior to, and after, the in-school eyecare. Surveys were employed to obtain visual histories from parents/teachers. School records and statutory documents were reviewed for diagnostic and learning disability classifications. Visual function and ocular health were profiled at baseline and significant visual deficits identified. Where such deficits were previously unrecognised, untreated or not compensated for (e.g. correction of refractive error, enlargement of educational material) they were recorded as 'unmet visual need'. At follow-up, 2-5 months after initial (baseline) measures, eye examinations, parent/teacher surveys and behaviour observations were repeated. Follow-up measures were used to determine if measurable improvements were evident in visual function, ocular health, the level of unmet need and classroom behaviour following implementation of in-school eyecare. RESULTS: 199 participants completed baseline and follow-up measures. 122 (61%) participants presented with at least one significant visual or ocular health deficit and 90 (45%) participants had at least one unmet visual need. Younger pupils and those with no previous history of eyecare were more likely to demonstrate unmet visual needs at baseline (OR 1.12 95% CI 1.03 to 1.21) p = 0.012; (OR 4.44 95% CI 1.38 to 14.29 p = 0.007 respectively). On follow-up, the number of pupils with unmet visual needs dropped significantly to 36 (18%) (McNemar's test p<0.001). Visual and behavioural metrics of participants without significant visual deficits or whose visual needs were adequately addressed at baseline remained relatively unchanged between baseline and follow-up (Wilcoxon signed rank p>0.05). Where significant refractive deficits were corrected at follow-up, near visual acuity improved significantly (Wilcoxon signed rank p = 0.013), however, poor spectacle compliance was a persistent cause of unmet visual need. Off-task behaviour reduced significantly after actions to address unmet visual needs were communicated to parents and teachers (Wilcoxon signed rank p = 0.035). CONCLUSIONS: The present study demonstrates for the first time measurable visual and behaviour benefits to children in special education settings when they receive comprehensive in-school eye examinations, on-site spectacle dispensing and jargon-free reporting of outcomes to teachers and parents.

Correction: In-school eyecare in special education settings has measurable benefits for children's vision and behaviour.

[This corrects the article DOI: 10.1371/journal.pone.0220480.].

Vascular cell responsiveness to Toll-like receptor ligands in carotid atheroma.

BACKGROUND: Atherosclerosis is potentiated by stimulation of Toll-like receptors (TLRs), which serve to detect pathogen associated molecular patterns (PAMPs). However little is known of which PAMPs may be present in atheroma, or capable of stimulating inflammatory signalling in vascular cells. MATERIALS AND METHODS: DNA extracted from human carotid atheroma samples was amplified and sequenced using broad-range 16S gene specific primers to establish historical exposure to bacterial PAMPs. Responsiveness of primary human arterial and venous endothelial and smooth muscle cells to PAMPs specific for each of the TLRs was assessed by measurement of interleukin-8 secretion and E-selectin expression. RESULTS: Extracts of atheromatous tissue stimulated little or no signalling in TLR-transfected HEK-293 cells. However, sequencing of bacterial DNA amplified from carotid atheroma revealed the presence of DNA from 17 different bacterial genera, suggesting historical exposure to bacterial lipopeptide, lipopolysaccharide and flagellin. All cells examined were responsive to the ligands of TLR3 and TLR4, poly inosine:cytosine and lipopolysaccharide. Arterial cells were responsive to a wider range of PAMPs than venous cells, being additionally responsive to bacterial flagellin and unmethylated cytosine-phosphate-guanosine DNA motifs, the ligands of TLR5 and TLR9, respectively. Cells were generally unresponsive towards the ligands of human TLR7 and TLR8, loxoribine and single stranded RNA. Only coronary artery endothelial cells expressed TLR2 mRNA and responded to the TLR2 ligand Pam(3)CSK(4). CONCLUSIONS: Vascular cells are responsive to a relatively diverse range of TLR ligands and may be exposed, at least transiently, to ligands of TLR2, TLR4, TLR5 and TLR9 during the development of carotid atheroma.

Change of visual acuity recording methods in clinical studies across the years.

PURPOSE: To report any differences in the visual acuity (VA) recording method used in peer-reviewed ophthalmology clinical studies over the past decade. METHODS: We reviewed the method of assessing and reporting VA in 160 clinical studies from 2 UK and 2 US peer-reviewed journals, published in 1994 and 2004. RESULTS: The method used to assess VA was specified in 62.5% of UK-published and 60% of US-published papers. In the results sections of the UK publications the VA measurements presented were Snellen acuity (n = 58), logMAR acuity (n = 20) and symbol acuity (n = 1). Similarly in the US publications the VA was recorded in the results section using Snellen acuity (n = 60) and logMAR acuity (n = 14). Overall 10% of the authors appeared to convert Snellen acuity measurements to logMAR format. Five studies (3%) chose to express Snellen-type acuities in decimal form, a method which can easily lead to confusion given the increased use of logMAR scoring systems. CONCLUSION: The authors recommend that to ensure comparable visual results between studies and different study populations it would be useful if clinical scientists worked to standardized VA testing protocols and reported results in a manner consistent with the way in which they are measured.

The BN51 protein is a polymerase (Pol)-specific subunit of RNA Pol III which reveals a link between Pol III transcription and pre-rRNA processing.

The three eukaryotic nuclear RNA polymerase (Pol) contain common and unique subunits. Cloning of the unique Pol III subunit genes in yeast cells has revealed a potential homolog in the mammalian system, the BN51 gene. The human BN51 gene was originally isolated as a suppressor of a temperature-sensitive cell cycle mutant of BHK cells (tsBN51). Although tsBN51 cells have a marked decrease in RNA Pol III activity at the nonpermissive temperature, direct biochemical evidence for the BN51 protein being a human Pol III subunit was lacking. Using antibodies directed against the BN51 protein, we show the following: (i) the BN51 protein copurifies with Pol III activity, (ii) Pol III activity can be specifically immunoprecipitated from HeLa nuclear extracts, and (iii) the immunopurified BN51 complex is active in restoring both nonspecific and promoter-specific Pol III activity. Our findings provide direct biochemical evidence for BN51 being a Pol III-specific subunit. Despite the fact that BN51 is not a subunit of Pol I, the production of mature Pol I transcripts is inhibited in tsBN51 cells at the nonpermissive temperature. tsBN51 cells appear defective in processing the 32S precursor rRNA into mature 5.8S and 28S rRNA at the nonpermissive temperature. We surmise that ribosome assembly has halted because of the loss of Pol III transcripts. Thus, there is regulation of the synthesis of mature Pol I transcripts by a posttranscriptional mechanism based on the availability of Pol III transcripts.

Pharmacokinetics of 5-fluorouracil following different routes of intrahepatic administration in the canine model.

In an effort to achieve high concentrations of 5-fluorouracil (5-FUra) in the hepatic circulation while minimizing systemic exposure, several routes of intrahepatic administration were compared in the canine model. To ascertain these data, 5-FUra (30 mg/kg) was given as a bolus into either a systemic vein (femoral vein), hepatic artery, hepatic artery distal to its ligation after hepatic dearterialization, or through the portal vein. Three dogs were studied for each route with concomitant blood samples taken from the inferior vena cava and hepatic vein at 1, 2, 3, 5, 10, 15, 30, and 60 min after injection. 5-FUra levels were determined in plasma by high-pressure liquid chromatography. Blood flow in the portal vein and hepatic artery was measured by an electromagnetic flowmeter. The data were best described by a multicompartmental model including the measured flows. Hepatic components of the model were separate arterial and portal compartments, with elimination from each described by linear kinetics. Analysis of the results indicated that the highest hepatic levels with the least systemic exposure, as indicated by drug levels in hepatic and peripheral vein, were realized following hepatic artery administration distal to its ligation after hepatic dearterialization.

Liposome-entrapped diethylstilbestrol effect on prostate gland and plasma testosterone levels in rats.

The effects of liposome-encapsulated diethylstilbestrol (DES) on the size of the ventral prostate gland and total testosterone levels in rats were studied. DES was encapsulated in phosphatidycholine-cholesterol-stearylamine-alpha-tocopherol containing multilamellar liposomes in a molar ratio of 4:5:1:0.01. The liposome suspension or free DES plus blank liposomes were administered sc on days 1, 3, and 5 at a dose of 400, 87, or 12 micrograms/kg. Plasma testosterone values showed a decrease with dose for animals treated with either entrapped DES or free DES. Prostate gland weight per g animal and prostatic protein mg per g animal on day 7 were significantly decreased in the treated animals compared to those in controls dosed with DES plus buffer containing liposomes. In addition, there was a body weight loss for the high dose DES-encapsulated animals and for high and medium dose DES plus blank liposome-treated and blank liposome-treated animals over the treatment period, although only the DES-encapsulated group value was statistically significant (P less than 0.05). Animals at the other doses did not lose weight, but exhibited weight gains which were less than those observed for sham-injected animals. Rats that received 7 micrograms/kg liposome-entrapped DES for 4 weeks had significantly lower prostate gland weights, prostatic protein levels, and testosterone levels than control animals receiving the same regimen of free DES plus blank liposomes. Results from the studies indicate that liposome-entrapped DES was more effective in decreasing the size of the prostate gland and that the desired therapeutic end point (prostate ablation) may be attained with a lower dose of DES, which would decrease the risk of weight loss in the experimental animals.

Paradoxical inhibition by aspirin of naloxone-induced adrenocorticotropin secretion in myotonic dystrophy.

The ACTH response to endogenous or exogenous CRH is increased in patients with myotonic dystrophy (DM), possibly because of abnormal function of cAMP-dependent protein kinases in this condition. Arachidonic acid (AA) metabolites are believed to interact with the cAMP-dependent second messenger system activated by CRH; therefore, drugs that interfere with AA metabolism may alter ACTH secretion in DM. In this study, seven DM patients were given naloxone, which stimulates endogenous CRH release, and aspirin, which inhibits the synthesis of prostaglandins from AA via the cyclooxygenase metabolic pathway. Pretreatment with aspirin reduced the mean integrated ACTH response to naloxone by 33% (P < 0.05). However, the corresponding 18% reduction in cortisol levels was not statistically significant (P > 0.10). These findings are in contrast to those of a previous study using an identical protocol, in which aspirin increased the ACTH response to naloxone in six normal volunteers. This difference between DM and control subjects is consistent with the hypothesis that the interaction between AA metabolites and the cAMP-dependent protein kinase-A second messenger system is abnormal in the corticotrophs of persons with DM.

Aspirin increases the human hypothalamic-pituitary-adrenal axis response to naloxone stimulation.

Prostaglandins are believed to influence hypothalamic-pituitary-adrenal (HPA) axis function, but their specific effects on ACTH and cortisol secretion in humans are unclear. Acetylsalicylic acid (aspirin) blocks the synthesis of prostaglandins from arachidonic acid. We studied the effects of oral aspirin on the plasma ACTH and cortisol responses to iv naloxone, which increases endogenous CRH release, in six normal volunteers and on the adrenocortical response to synthetic ACTH boluses in seven other healthy subjects, using placebo-controlled, single blinded protocols. Aspirin pretreatment significantly increased the ACTH response to naloxone [mean peak increase from basal, 8.3 +/- 1.2 vs. 5.9 +/- 0.8 pmol/L (P < 0.05); mean integrated response, 431.9 +/- 51.5 vs. 295.1 +/- 26.6 pmol/L.min (P < 0.005); for aspirin/naloxone and placebo aspirin/naloxone, respectively]. However, the corresponding cortisol results did not show statistically significant differences (P < 0.20). The mean integrated ACTH and cortisol responses were 46% and 26% greater with aspirin, respectively. Aspirin did not influence the cortisol responses to synthetic ACTH administration given according to a dose-response protocol. We conclude that aspirin augments the HPA axis response to naloxone stimulation in normal humans without having a direct effect at the adrenal level. The action of aspirin on the human HPA axis is probably mediated via inhibition of cyclooxygenase, resulting in changes in arachidonic acid metabolites, which influence ACTH release from corticotrophs.

CRH-mediated pituitary-adrenal responses are inhibited by nifedipine in humans.

Sustained CRH-stimulated ACTH release in vitro depends on Ca2+ influx and is inhibited 30-40%, but not delayed, by dihydropyridine Ca2+ channel blockers. In five normal humans, we found that nifedipine pretreatment reduced integrated ACTH responses to the CRH-mediated stimulus of fenfluramine by 28% and cortisol responses by 34%, results comparable with those from in vitro reports. Nifedipine did not alter the timing of peak hormonal responses. We conclude that (1) in humans, nifedipine inhibits ACTH release by fenfluramine by blocking Ca2+ influx via L-type channels in corticotrophs; (2) the magnitude of fenfluramine-stimulated CRH release is probably unaltered by nifedipine and (3) because the timing is unaltered, nifedipine does not affect the rate of CRH delivery to the corticotroph.

Plasma pharmacokinetics of intravenously administered atropine in normal human subjects.

The pharmacokinetics of atropine (dl-hyoscyamine) was studied in six normal volunteers following a single 1-mg intravenous dose of atropine. Atropine plasma levels were collected for 24 hours and analyzed by radioimmunoassay. Pulse rates were monitored and compared with predose values in each subject. Atropine plasma concentrations were fitted by least-squares regression analysis. The observed maximal increase in pulse rate, at 12 to 16 minutes after the dose, correlated with the maximum predicted tissue levels of atropine based on the computer fit of the plasma atropine concentration-time data. No correlation between the time of maximum response and atropine plasma concentrations was observed. The average half-life of atropine was 4.125 hours. This data may be used to design a multiple-dosing regimen for intravenous atropine in patients.