A novel cationic niosome formulation for gene delivery to the retina

Niosomes represent a recent promising approach for gene delivery purposes. We elaborated on a novel niosome formulation based on the 2,3-di(tetradecyloxy)propan-1-amine cationic lipid, combined with squalene and polysorbate 80 to evaluate the transfection efficiency in rat retinas. Niosomes prepared by the solvent emulsification-evaporation technique were mixed with the pCMSEGFP plasmid to form lipoplexes which were characterized in terms of morphology, size, surface charge, and DNA condensation, protection and release. In vitro studies were conducted to evaluate transfection efficiency, viability and internalization mechanism in HEK-293 and ARPE-19 cells. The efficacy of the most promising formulation was evaluated in rat eyes by monitoring the expression of the EGFP after intravitreal and subretinal injections. Lipoplexes at 15/1 ratio were 200nm in size, 25mV in zeta potential and exhibited spherical morphology. At this ratio, niosomes condensed and protected the DNA from enzymatic digestion. Lipoplexes successfully transfected HEK-293 and specially ARPE-19 cells, without affecting the viability. Whereas lipoplexes entered mainly retinal cells by clathrin-mediated endocytosis, HEK-293 cells showed a higher caveolae-dependent entry. After ocular administration, the expression of EGFP was detected in different cells of the retina depending on the administration route. This novel niosome formulation represents a promising approach to deliver genetic material into the retina to treat inherited retinal diseases.

Holographic grating stability: influence of 4,4'-azobis (4-cyanopentanoic acid) on various spatial frequencies

This paper presents the results obtained when holographic gratings were stored with a spatial frequency of 954 and 2663 lines/mm in transmission geometry and 4600 lines/mm in reflection geometry in a polyvinyl alcohol/acrylamide-based material. Photopolymers are materials that give good results at low frequencies, but their diffraction efficiency (DE) decreases at high frequencies. A chain transfer agent, 4,4'-azobis (4-cyanopentanoic acid) (ACPA) was incorporated in the material composition to improve spatial resolution. Furthermore, a curing process was applied to the stored gratings in order to maintain the DE stable over time. The DE and shrinkage for symmetric holographic transmission and reflection gratings were measured to evaluate their quality and quantify the improvement produced by ACPA.

N-terminal pro-brain natriuretic peptide level determined at different times identifies transient ischaemic attack patients with atrial fibrillation

BACKGROUND AND PURPOSE

The etiological classification of patients with transient ischaemic attack (TIA) is a difficult endeavor and the use of serum biomarkers could improve the diagnostic accuracy. The aim of this study was to correlate atrial fibrillation, the main cardioembolic etiology (CE), with different serum biomarkers measured in consecutive TIA patients.

METHODS

The concentrations of interleukin-6 (IL-6), tumor necrosis factor-alpha, neuron-specific enolase, high-sensitivity C-reactive protein, IL-1-α and the N-terminal pro-B type natriuretic peptide (NT-proBNP) were quantified in the serum of 140 patients with TIA and 44 non-stroke subjects. Measurements were performed at different times throughout evolution: within 24 h of symptoms onset and at days 7 and 90.

RESULTS

With the exception of IL-6, all biomarkers were higher in TIA patients than in controls. NT-proBNP was significantly related to the presence or new diagnosis of AF at all time points analyzed. Furthermore, the baseline NT-proBNP level was significantly higher than values at the 7-day and 90-day follow-up. For this reason, different cut-off values were obtained at different times: 313 pg/ml at baseline [odds ratio (OR) = 18.99, P < 0.001], 181 pg/ml at 7 days (OR = 11.4, P = 0.001) and 174 pg/ml (OR = 8.46, P < 0.001) at 90 days.

CONCLUSION

High levels of NT-proBNP determined during the first 3 months after a TIA were associated with AF. Consequently, this biomarker may be useful to reclassify undetermined TIA patients as having disease of CE.

Differentiation of white wines by their aromatic index

Wines from four Galician white varieties (Albariño, Loureira, Treixadura and Dona Branca) with 1992 to 1995 vintages have been analysed, in order to obtain their characterisation by the aromatic index. Monoterpenes, higher alcohols, ethyl esters, fatty acids, acetates, volatile phenols and heavy sulphur compounds were analysed by gas chromatography alone and together with mass spectrometry. Flavour compositions were similar for each wine obtained from grapes harvested in different years. Comparisons between odour unit values (OUV) from each wine variety and from these vintages were similar. However, odour profiles of Galician wines from these years were clearly differentiated. A correct differentiation could be achieved between samples elaborated with different varieties, when principal component and linear discriminant analysis were applied to the OUV data.

Oligochitosan polyplexes as carriers for retinal gene delivery

Non-viral gene therapy represents a promising approach for the treatment of retinal diseases. However, the lack of an efficient carrier hampers the implementation of this therapy. In this study, we evaluated low molecular weight ultrapure oligochitosans for the delivery of the pCMS-EGFP plasmid into the rat retina cells after subretinal and intravitreal administrations. Polyplexes were technologically characterized. Resulting polyplexes based on ultrapure oligochitosans were slightly spherical, protected the plasmid against enzymatic digestion, and their charge and size values ranged from 8 to 14 millivolts and from 150 to 69 nm respectively depending on the N/P ratio. In HEK-293 cultured cells, transfection efficiency significantly increased from 12% to 30% when pH decreased from 7.4 to 7.1 (data normalized to Lipofectamine™ 2000). However, no significant transfection was detected in ARPE-19 cultured cells. Subretinal administrations transfected mainly the pigmented cells of the retinal pigment epithelium and the light sensitive photoreceptor cells, whereas intravitreal injections transfected cells in the ganglion cell layer, blood vessels in the inner layers of the retina and photoreceptors. These results support the potential use of oligochitosans for delivering genetic material into retinal cells in vivo.

Low molecular weight oligochitosans for non-viral retinal gene therapy

Ultrapure oligochitosans have recently been evaluated as a promising tool for corneal gene therapy; however, there are no reports regarding the potential use of this polymer in other ocular tissues. We have prepared and characterized at pH 7.1 oligochitosan/pCMS-EGFP polyplexes to evaluate the transfection efficiency in rat retinas after subretinal and intravitreal administration. Polyplexes were characterized in terms of shape, size, surface charge, DNA condensation, and transfection efficiency in HEK-293 and ARPE-19 culture cells. Polyplexes were positively charged, around 10 mV, and size oscillated between 256.5 ± 56 and 67.3 ± 0.44 nm, depending on the nitrogenous/phosphate ratio. Polyplexes efficiently protected the plasmid against enzymatic digestion. A drastic increase in transfection efficiency was observed when pH slightly decreased from 7.4 to 7.1 in both HEK-293 (from 19.1% to 51.5%) and ARPE-19 (from 2.0% to 36.5%) cells (data normalized to Lipofectamine™ 2000). In rat retinas, subretinal administrations transfected cells mainly in the RPE layer, whereas intravitreal injections transfected cells in the inner nuclear and plexiform layers of the retina and mainly in the ganglion cell layer. This study establishes the base for future treatments of genetic retinal disorders with low molecular weight oligochitosan polyplexes.

Microwave-assisted extraction and ultrasonic slurry sampling procedures for cobalt determination in geological samples by electrothermal atomic absorption spectroscopy

Slurry sampling is compared to microwave-assisted acid digestion for cobalt determination in soil/sediment samples by electrothermal atomic absorption spectrometry (ETAAS). Furnace temperature programs and appropriate amounts of three chemical modifiers were optimised in order to get the highest signals and good separations between the atomic and background signals. Using nitric acid (0.5% (v/v)) as liquid medium, no chemical modifier was needed. The detection limit, based on integrated absorbance, was 0.04mugg(-1) for digests and slurries. Within-batch precision and analytical recoveries were satisfactory for both procedures. Accuracy was tested by analysing a reference soil and a sediment from IRMM. The methods were further compared employing a set of roadside soils and estuarine sediments. As no significant differences (95% confidence) were found, practical analytical properties were suggested in order to select one of them.

Impact of liposomal amphotericin B on renal function in critically ill patients with renal function impairment

OBJECTIVE

To assess the tolerability of liposomal amphotericin B (L-AmB) in critically ill patients with elevated serum creatinine concentrations (Cr) (> 1.5 mg/dL) at starting L-AmB therapy.

METHODS

Retrospective, multicenter, comparative study of two cohorts of critically ill patients treated with L-AmB during 3 or more days, the difference between them was the level of Cr at the beginning of treatment. A cutoff value of Cr of 1.5 mg/dL was established. Patients undergoing extrarenal depuration procedures before or 48 hours after starting L-AmB were excluded. The primary endpoint was the difference between Cr values at the end of treatment as compared with Cr at starting L-AmB. Secondary endpoints were treatment-related withdrawals, need of extrarenal depuration techniques, and treatment-related severe adverse events. Demographic data, underlying illness, indication of L-AmB therapy, concomitant risk factors of nephrotoxicity, and vital status at ICU and hospital discharge were recorded.

RESULTS

A total of 122 patients admitted to 26 ICUs (16 with Cr > 1.5 g/dL; 106 with normal Cr levels) were recruited. Main reasons for the use of L-AmB in both groups were the broad spectrum of the drug and the presence of hemodynamic instability. L-AmB was administered as first-line treatment in 68.8% of patients with elevated Cr and in 52.8% with normal Cr. The APACHE II score on ICU admission was 25 in patients with elevated Cr and 17 in those with normal Cr values (p < 0.001). Duration of treatment with L-AmB was 16 and 12 days in patients with elevate and normal Cr values, respectively, with a mean dose of 3.5 vs 3.9 mg/kg/day. The use of concomitant nephrotoxic drugs, mortality rate, and ICU and hospital length of stay were similar in both cohorts. In patients with renal function impairment at the initiation of L-AmB treatment, an absolute decrease of Cf-Ci of 1.08 mg/dL was observed (P < 0.001). A decrease of Cr levels to normal limits was observed in 50% of the patients; in 37.5% of patients there was a decrease but normal levels were not achieved, whereas a Cr increased occurred in only one (6.25%) patient. None of the patients required withdrawal of L-AmB or use of extrarenal depuration procedures. Treatment-related severe adverse events were not reported.

CONCLUSIONS

In critically ill patients with impaired renal function, the impact of L-AmB on renal function was minimal. L-AmB can be used for the treatment of fungal infections in critically ill patients independently of renal function at the initiation of treatment.

High performance magnetoimpedance in FeNi/Ti nanostructured multilayers with opened magnetic flux

Magnetic [FeNi (170 nm)/Ti (6 nm)]3/Cu (L(cu) = 250 or 500 nm)/[Ti (6 nm)/FeNi (170 nm)]3 multilayers were designed with focus on high frequency applications. They were deposited onto glass or a microfluidic system compatible flexible Ciclo Olefin Copolymer substrate and comparatively tested. A maximum sensitivity for the total impedance of 110%/Oe was obtained for a driving current frequency of 30 MHz for [FeNi/Ti]3/Cu (L(cu) = 500 nm)/[Ti/FeNi]3 multilayers deposited onto a glass substrate and 45%/Oe for a driving current frequency of 65 MHz for the same multilayers deposited onto the flexible polymer substrate, a very promising result for applications. The possibility of using flexible substrate/[FeNi/Ti],/Cu/[Ti/FeNi]3 multilayers as MI pressure-sensitive elements was also demonstrated.

Effect of the calcium to phosphorus ratio on the setting properties of calcium phosphate bone cements

α-Tricalcium phosphate (α-TCP) has become the main reactant of most experimental and commercial ceramic bone cements. It has calcium-to-phosphorus (Ca/P) ratio of 1.50. The present study expands and reports on the microstructures and mechanical properties of calcium phosphate (CP) cements containing sintered monolithic reactants obtained in the interval 1.29 < Ca/P < 1.77. The study focuses on their cement setting and hardening properties as well as on their microstructure and crystal phase evolution. The results showed that: (a) CP-cements made with reactants with Ca/P ratio other than 1.50 have longer setting and lower hardening properties; (b) CP-cements reactivity was clearly affected by the Ca/P ratio of the starting reactant; (c) reactants with Ca/P < 1.50 were composed of several phases, calcium pyrophosphate and α- and β-TCP. Similarly, reactants with Ca/P > 1.50 were composed of α-TCP, tetracalcium phosphate and hydroxyapatite; (d) only the reactant with Ca/P = 1.50 was monophasic and was made of α-TCP, which transformed during the setting into calcium deficient hydroxyapatite; (e) CP-cements developed different crystal microstructures with specific features depending on the Ca/P ratio of the starting reactant.

Human neuroblastoma cultures for biorobotics

This paper introduces a new biorobotic system using human neuroblastoma cultures and centre of area learning for basic robotic guidance. Multielectrode Arrays Setups have been designed for direct culturing neural cells over silicon or glass substrates, providing the capability to stimulate and record simultaneously populations of neural cells. The main objective of this work will be to control a robot using this biological neuroprocessor and a new simple centre of area learning scheme. The final system could be applied for testing how chemicals affect the behaviour of the robot or to establish the basis for new hybrid optogenetic neuroprostheses based on stimulating optically genetic-modified neurons.

Ultrasound monitoring of the setting of calcium-based bone cements

In this study, the setting of calcium-sulphate (CS) and -phosphate (CP) based bone cements (BCs) was monitored by ultrasound. The objective was to link acoustic and material properties of ceramic-based BCs from the early stages of the cement curing process. The powder phase of the CS-cement consisted of CS hemihydrate; the CP-cement was a mixture of alpha-tricalcium phosphate, CS dihydrate and hydroxyapatite. For the CS-cement, the acoustic impedance z (c)(t), the speed of sound c (c)(t) and the density ρ(c)(t) were measured at the interval of liquid-to-powder ratios LPRs from 0.20 to 3.00 ml/g. For the CP-cement, the acoustic characteristics obtained were the z (c)(t) and the reflection coefficient R (p,c)(t), and the LPRs ranged from 0.30 to 0.40 ml/g. The resulting acoustic properties indicated that CP- and CS-cements exhibited distinctly different curing behaviour; while CS-cement expanded, CP-cement shrank with time.