Transnasal humidified rapid-insufflation ventilatory exchange (THRIVE) in children: a randomized controlled trial.

BACKGROUND: Transnasal humidified rapid-insufflation ventilatory exchange (THRIVE) was introduced to adult anaesthesia to improve the safety of airway management during apnoea before intubation. The objective of our study was to determine whether THRIVE safely prolongs apnoeic oxygenation in children. METHODS: This was a randomized controlled trial in 48 healthy children, with normal airways and cardiorespiratory function, in age groups 0-6 and 7-24 months, 2-5 and 6-10 yr old, presenting for elective surgery or imaging under general anaesthesia. All children were induced with sevoflurane, O2, and N2O, followed by muscle relaxation with rocuronium, and standardized preoxygenation with bag-and-mask ventilation. The control arm received jaw support during apnoea, whereas the THRIVE arm received jaw support during apnoea and age-specific flow rates. The primary outcome was to demonstrate that children allocated to THRIVE maintain transcutaneous haemoglobin saturation at least twice as long as the expected age-dependent apnoea time in the control group. RESULTS: Both study arms (each n=24) were similar in age and weight. The apnoea time was significantly shorter in the control arm: average 109.2 (95% CI 28.8) s in the control arm and 192 s in the THRIVE arm (0-6 months), 147.3 (95% CI 18.9) and 237 s (7-24 months), 190.5 (95% CI 15.3) and 320 s (2-5 yr), and 260.8 (95% CI 37.5) and 430 s (6-10 yr), respectively. Average transcutaneous haemoglobin saturation remained at 99.6% (95% CI 0.2) during THRIVE. Transcutaneous CO2 increased to a similar extent in both arms, with 2.4 (95% CI 0.5) mm Hg min-1 for the control arm and 2.4 (95% CI 0.4) mm Hg min-1 for the THRIVE arm. CONCLUSION: Transnasal humidified rapid-insufflation ventilatory exchange prolongs the safe apnoea time in healthy children but has no effect to improve CO2 clearance. CLINICAL TRIAL REGISTRATION: ACTRN12615001319561.

Monitoring the endocytosis of magnetic nanoparticles by cells using permanent micro-flux sources.

Trapping of cells is essential to perform basic handling operations in cell-based microsystems, such as media exchange, concentration, cell isolation and cell sorting. Cell trapping by magnetophoresis typically requires cell labeling with magnetic nanoparticles. Here we report on endocytotic uptake of 100 nm magnetic nanoparticles by Human Embryonic Kidney 293 cells. The attraction of labeled cells by micro-magnet arrays characterised by very high magnetic field gradients (≤106 T/m) was studied as a function of labeling conditions (nanoparticle concentration in the extracellular medium, incubation time). The threshold incubation conditions for effective magnetophoretic trapping were established. This simple technique may be exploited to minimise the quantity of magnetic nanoparticles needed for efficient cell trapping, thus reducing stress or nanoparticle-mediated toxicity. Nanoparticle internalization into cells was confirmed using both confocal and Transmission Electron Microscopy (TEM).

Development and applications of a DNA labeling method with magnetic nanoparticles to study the role of horizontal gene transfer events between bacteria in soil pollutant bioremediation processes.

Horizontal gene transfers are critical mechanisms of bacterial evolution and adaptation that are involved to a significant level in the degradation of toxic molecules such as xenobiotic pesticides. However, understanding how these mechanisms are regulated in situ and how they could be used by man to increase the degradation potential of soil microbes is compromised by conceptual and technical limitations. This includes the physical and chemical complexity and heterogeneity in such environments leading to an extreme bacterial taxonomical diversity and a strong redundancy of genes and functions. In addition, more than 99 % of soil bacteria fail to develop colonies in vitro, and even new DNA-based investigation methods (metagenomics) are not specific and sensitive enough to consider lysis recalcitrant bacteria and those belonging to the rare biosphere. The objective of the ANR funded project "Emergent" was to develop a new culture independent approach to monitor gene transfer among soil bacteria by labeling plasmid DNA with magnetic nanoparticles in order to specifically capture and isolate recombinant cells using magnetic microfluidic devices. We showed the feasibility of the approach by using electrotransformation to transform a suspension of Escherichia coli cells with biotin-functionalized plasmid DNA molecules linked to streptavidin-coated superparamagnetic nanoparticles. Our results have demonstrated that magnetically labeled cells could be specifically retained on micromagnets integrated in a microfluidic channel and that an efficient selective separation can be achieved with the microfluidic device. Altogether, the project offers a promising alternative to traditional culture-based approaches for deciphering the extent of horizontal gene transfer events mediated by electro or natural genetic transformation mechanisms in complex environments such as soil.

Microfluidic immunomagnetic cell separation using integrated permanent micromagnets.

In this paper, we demonstrate the possibility to trap and sort labeled cells under flow conditions using a microfluidic device with an integrated flat micro-patterned hard magnetic film. The proposed technique is illustrated using a cell suspension containing a mixture of Jurkat cells and HEK (Human Embryonic Kidney) 293 cells. Prior to sorting experiments, the Jurkat cells were specifically labeled with immunomagnetic nanoparticles, while the HEK 293 cells were unlabeled. Droplet-based experiments demonstrated that the Jurkat cells were attracted to regions of maximum stray field flux density while the HEK 293 cells settled in random positions. When the mixture was passed through a polydimethylsiloxane (PDMS) microfluidic channel containing integrated micromagnets, the labeled Jurkat cells were selectively trapped under fluid flow, while the HEK cells were eluted towards the device outlet. Increasing the flow rate produced a second eluate much enriched in Jurkat cells, as revealed by flow cytometry. The separation efficiency of this biocompatible, compact micro-fluidic separation chamber was compared with that obtained using two commercial magnetic cell separation kits.

Contactless diamagnetic trapping of living cells onto a micromagnet array.

This paper focuses on the application of magnetophoresis to a new cell patterning method. The principle was demonstrated by using a CoPt micromagnet array, producing regularly spaced magnetic traps where cells were confined without any contact under the effect of negative magnetophoresis. To obtain this effect, yeast cells (Saccharomyces cerevisiae), which are diamagnetic, were placed in an aqueous solution enriched in paramagnetic ions. Unlabeled (non-magnetic) cell manipulation by magnetophoresis requires the production of high magnetic field gradients, ensuring significant forces. Therefore, micromagnets are particularly interesting for our application, since the field gradient increases as magnet dimensions are reduced.

[Recent demographic trends in Italy according to the results of the October 1981 census]. / L'evolution demographique recente de l'Italie d'apres les resultats du recensement d'octobre 1981

PIP: Recent demographic trends in Italy are examined using the results of the 1981 census. The author notes that fertility continued to fall during the 1970s and that migration, although reduced in quantity, remains significant. The general pattern of internal migration continues to be from south to north, while an increasing trend to medium-size towns and suburban areas seems to have developed in northern and central Italy. In southern Italy urbanization is greater, particularly in coastal regions where tourism and new industrial plants have enhanced employment opportunities.^ieng