Design of Multi-Luminescent Silica-Based Nanoparticles for the Detection of Liquid Organic Compounds.

Tracer testing in reservoir formations is utilised to determine residual oil saturation as part of optimum hydrocarbon production. Here, we present a novel detection method of liquid organic compounds by monodisperse SiO2 nanoparticles (NPs) containing two luminophores, a EuIII:EDTA complex and a newly synthesised fluorophore based on the organic boron-dipyrromethene (BODIPY)-moiety. The particles exhibited stable EuIII PL emission intensity with a long lifetime in aqueous dispersion. The fluorescence of the BODIPY was also preserved in the aqueous environment. The ratiometric PL detection technique was demonstrated by using toluene and 1-octanol as model compounds of crude oil. The optimal synthesis conditions were found to give NPs with a diameter of ~100 nm, which is suitable for transport through porous oil reservoir structures. The cytotoxicity of the NPs was confirmed to be very low for human lung cell and fish cell lines. These findings demonstrate the potential of the NPs to replace the hazardous chemicals used to estimate the residual oil saturation. Moreover, the ratiometric PL detection technique is anticipated to be of benefit in other fields, such as biotechnology, medical diagnostics, and environmental monitoring, where a reliable and safe detection of a liquid organic phase is needed.

Stimuli-Responsive Polysaccharide Hydrogels and Their Composites for Wound Healing Applications.

There is a growing concern about wound care, since traditional dressings such as bandages and sutures can no longer meet existing needs. To address the demanding requirements, naturally occurring polymers have been extensively exploited for use in modern wound management. Polysaccharides, being the most abundant biopolymers, have some distinct characteristics, including biocompatibility and biodegradability, which render them ideal candidates for wound healing applications. Combining them with inorganic and organic moieties can produce effective multifunctional composites with the desired mechanical properties, high wound healing efficiencies and excellent antibacterial behavior. Recent research endeavors focus on the development of stimuli-responsive polysaccharide composites for biomedical applications. Polysaccharide composites, being sensitive to the local environment, such as changes of the solution temperature, pH, etc., can sense and react to the wound conditions, thus promoting an effective interaction with the wound. This review highlights the recent advances in stimuli-responsive polysaccharide hydrogels and their composites for use in wound healing applications. The synthetic approaches, physical, chemical, and biochemical properties as well as their function in wound healing will be discussed.

Photo- and Acid-Degradable Polyacylhydrazone-Doxorubicin Conjugates.

Light-mediated polymer degradation has attracted considerable attention in various applications, including photo-patterning, tissue engineering and photo-triggered drug delivery. In this study, we report the synthesis and characterization of a new, linear, main-chain photo- and acid-degradable copolymer based on acylhydrazone linkages. The polymer was synthesized via a step-growth copolymerization of adipic acid dihydrazide with a bifunctional poly(ethylene glycol) bearing benzaldehyde end-groups, under mild acidic conditions, to afford a hydrophilic PEG-alt-adipic acid (PEG-alt-AA) alternating copolymer. The synthesized polymer was characterized by size exclusion chromatography, proton nuclear magnetic resonance and attenuated total reflection-Fourier transform infrared spectroscopies. The main-chain photo- and acid-induced degradation of the copolymer in dimethylsulfoxide and water, respectively, was verified by UV-vis spectroscopy at light intensities as low as 0.1 mW cm-2 at λ = 254 nm. Next, a model anticancer drug, doxorubicin (DOX), was chemically linked to the polymer chain end(s) via acylhydrazone bond(s), resulting in amphiphilic PEG-alt-adipic acid-DOX (PEG-alt-AA-DOX) polymer-drug conjugates. The conjugates were self-assembled in water to form spherical nanoparticles, as evidenced by scanning and transmission electron microscopies. The irradiation of the self-assembled PEG-alt-AA-DOX conjugates with UV light and the decrease of the solution pH resulted in the disruption of the assemblies due to the photolysis and acidolysis of the acylhydrazone bonds, and the release of the therapeutic cargo.

Central line-associated bloodstream infection in childhood malignancy: Single-center experience.

BACKGROUND: Central line-associated bloodstream infection (CLABSI) is a common complication in children with malignancy, often leading to prolonged hospitalization, delay in chemotherapy or catheter removal. This retrospective epidemiological study reviewed 91 children with malignancy over a 5 year period between 2011 and 2015 and analyzed potential risk factors for CLABSI. METHODS: Symptoms, laboratory and microbiology characteristics, subsequent treatment and outcome were recorded and analyzed. All the collected data were processed through SPSS for statistical analysis. RESULTS: Among 40 episodes of CLABSI recorded in 30 patients, the rate of CLABSI was estimated as 2.62 episodes per 1,000 days of central venous catheter (CVC) carriage. Most of the bacterial pathogens isolated in CLABSI episodes were Gram positive, including different strains of staphylococci, while Gram-negative bacteria were involved in 30% of episodes. Invasive mycosis was isolated in 7.5% of episodes, accounting for the highest catheter removal rate. Intensive chemotherapy and prolonged hospitalization proved to be independent risk factors for CVC infection. In children with neutropenia, the risk for CLABSI was also fourfold greater (P = 0.001). Children with leukemia had a fivefold greater risk for CLABSI (P = 0.005). Finally, although 36% of patients received antibiotic lock therapy, in 15% of these patients catheter replacement could not be avoided due to persistent serious infection. CONCLUSIONS: Younger age, neutropenia, hematologic malignancy and longer catheterization are important risk factors for CLABSI, but further research is required for the prevention of catheter-related infection in children with malignancy.

Gender differences in the prevalence and clustering of multiple health risk behaviours in young adults.

AIMS: To estimate the sex-stratified prevalence and clustering of 14 behavioural and metabolic health risk factors in emerging adulthood. BACKGROUND: The high prevalence and the clustering of risk factors multiply health consequences and increase the threat to the future health and quality of life of young adults. DESIGN: Descriptive cross-sectional study. METHODS: During November-December 2012, we assessed 14 lifestyle characteristics of 1058 1st year university students' that were classified as: healthy (score = 0), unhealthy (score = 1) and high-risk unhealthy (score = 2). We subsequently created a Multiple Health Risk Behaviours Index by summing the score of each behaviour adjusted to 0-100. RESULTS: Only 0·3% of the students had one risk behaviour and 21·3% (male: 31·5%; female: 12·6%) had ≥10 of 14. Male students had higher risk index score. In adjusted regression analyses, female students had higher odds of reporting healthier behaviours in oral hygiene (tooth brushing), red meat and junk food consumption, binge drinking, cannabis/hashish/marijuana use and lower number of sexual partners and Body Mass Index. Male students reported higher physical activity. No statistically significant gender differences were noted for screen time/sedentary behaviours, condom use, smoking, sunburns, breakfast and fruit and vegetable consumption. CONCLUSION: Although health-compromising behaviours are highly prevalent in both men and women, they are gender-related, with males engaging in more health risk behaviours than females. Preventive interventions may need to focus on gender-informed approaches when targeting multiple health risk behaviours.

A simulation study on the effects of dendritic morphology on layer V prefrontal pyramidal cell firing behavior.

Pyramidal cells, the most abundant neurons in neocortex, exhibit significant structural variability across different brain areas and layers in different species. Moreover, in response to a somatic step current, these cells display a range of firing behaviors, the most common being (1) repetitive action potentials (Regular Spiking-RS), and (2) an initial cluster of 2-5 action potentials with short interspike interval (ISIs) followed by single spikes (Intrinsic Bursting-IB). A correlation between firing behavior and dendritic morphology has recently been reported. In this work we use computational modeling to investigate quantitatively the effects of the basal dendritic tree morphology on the firing behavior of 112 three-dimensional reconstructions of layer V PFC rat pyramidal cells. Particularly, we focus on how different morphological (diameter, total length, volume, and branch number) and passive [Mean Electrotonic Path length (MEP)] features of basal dendritic trees shape somatic firing when the spatial distribution of ionic mechanisms in the basal dendritic trees is uniform or non-uniform. Our results suggest that total length, volume and branch number are the best morphological parameters to discriminate the cells as RS or IB, regardless of the distribution of ionic mechanisms in basal trees. The discriminatory power of total length, volume, and branch number remains high in the presence of different apical dendrites. These results suggest that morphological variations in the basal dendritic trees of layer V pyramidal neurons in the PFC influence their firing patterns in a predictive manner and may in turn influence the information processing capabilities of these neurons.

Coding and decoding with dendrites.

Since the discovery of complex, voltage dependent mechanisms in the dendrites of multiple neuron types, great effort has been devoted in search of a direct link between dendritic properties and specific neuronal functions. Over the last few years, new experimental techniques have allowed the visualization and probing of dendritic anatomy, plasticity and integrative schemes with unprecedented detail. This vast amount of information has caused a paradigm shift in the study of memory, one of the most important pursuits in Neuroscience, and calls for the development of novel theories and models that will unify the available data according to some basic principles. Traditional models of memory considered neural cells as the fundamental processing units in the brain. Recent studies however are proposing new theories in which memory is not only formed by modifying the synaptic connections between neurons, but also by modifications of intrinsic and anatomical dendritic properties as well as fine tuning of the wiring diagram. In this review paper we present previous studies along with recent findings from our group that support a key role of dendrites in information processing, including the encoding and decoding of new memories, both at the single cell and the network level.

Downregulation of lung mitochondrial prohibitin in COPD.

Prohibitins (PHB1 and PHB2) are versatile proteins located at the inner mitochondrial membrane, maintaining normal mitochondrial function and morphology. They interact with the NADH dehydrogenase protein complex, which is essential for oxidoreductase activity within cells. However, their expression in lung epithelium, especially in smokers and patients with inflammatory lung diseases associated with increased oxidative stress, such as COPD, is unknown. Lung tissue specimens from 45 male subjects were studied: 20 COPD patients [age: 65.7 ± 5.8 years, smoking: 84.6 ± 33.6 pack-years, FEV(1) (%pred.): 58.7 ± 14.6, FEV(1)/FVC (%): 63.8 ± 9.4], 15 non-COPD smokers [age: 59.0 ± 12.1 years, smoking: 52.5 ± 20.8 pack-years, FEV(1) (%pred.): 85.5 ± 14.2, FEV(1)/FVC (%): 78.5 ± 4.7] and 10 non-smokers. Quantitative real-time PCR experiments were carried out for PHB1 and PHB2, using ß-actin as internal control. Non-COPD smokers exhibited lower PHB1 mRNA levels when compared to non-smokers (0.55 ± 0.06 vs. 0.90 ± 0.06, P = 0.043), while PHB1 expression was even further decreased in COPD patients (0.32 ± 0.02), a statistically significant finding vs. both non-COPD smokers (P = 0.040) and non-smokers (P < 0.001). By contrast, PHB2 levels were similar among the three study groups. Western blot analysis for the PHB1 protein verified the qPCR results (non-smokers: 1.77 ± 0.13; non-COPD smokers: 0.97 ± 0.08; COPD patients: 0.59 ± 0.10, P = 0.007). Further analysis revealed that PHB1 downregulation in COPD patients cannot be attributed solely to smoking, and that PHB1 expression levels are associated with the degree of airway obstruction [FEV(1) (P(mRNA) = 0.004, P(protein) = 0.014)]. The significant downregulation of PHB1 in COPD and non-COPD smokers in comparison to non-smokers possibly reflects a distorted mitochondrial function due to decreased mitochondrial stability, especially in the mitochondria of COPD patients.

Deregulation of apoptosis mediators' p53 and bcl2 in lung tissue of COPD patients.

Abnormal apoptotic events in chronic obstructive pulmonary disease (COPD) subvert cellular homeostasis and may play a primary role in its pathogenesis. However, studies in human subjects are limited. p53 and bcl2 protein expression was measured by western blot on lung tissue specimens from 43 subjects (23 COPD smokers and 20 non-COPD smokers), using beta-actin as internal control. Additionally, p53 and bcl2 expression patterns were evaluated by immunohistochemistry in formalin-fixed, paraffin-embedded lung tissue sections from the same individuals. Western blot analysis showed statistically significant increased p53 protein levels in COPD smokers in comparison with non-COPD smokers (p = 0.038), while bcl2 protein levels were not statistically different between the two groups. Lung immunohistochemistry showed increased ratio of positive p53-stained type II pneumocytes/total type II pneumocytes in COPD smokers compared to non-COPD smokers (p = 0.01), whereas the p53 staining ratio in alveolar macrophages and in lymphocyte-like cells did not differ statistically between the two groups. On the other hand, bcl2 expression did not differ between the two groups in all three cell types. The increased expression of pro-apoptotic p53 in type II pneumocytes of COPD patients not counterbalanced by the anti-apoptotic bcl2 could reflect increased apoptosis in the alveolar epithelium of COPD patients. Our results confirm previous experiments and support the hypothesis of a disturbance in the balance between the pro- and anti-apoptotic mediators in COPD.