Bicaval dual-lumen cannula for venovenous extracorporeal membrane oxygenation: Avalon© cannula in childhood disease.

Severe acute refractory respiratory failure is considered a life-threatening situation, with a high mortality of 40 to 60%. When conservative oxygenation methods fail, a lifesaving measure is the introduction of extracorporeal membrane oxygenation (ECMO). Venovenous ECMO (VV-ECMO) is a preferred modality of support for patients with refractory acute respiratory failure. Specifically, bicaval VV-ECMO is a well-recognized and validated therapy, where single or double periphery venous access is used for the insertion of two differently sized cannulas in order to achieve adequate blood oxygenation. Compared to venoarterial ECMO, in VV-ECMO, the rate of complications, such as thrombosis, bleeding, infection and ischemic events, is lower. On the other hand, the size and insertion location is an obstacle to patient mobilization. This is a considerable problem for patients where the time interval for lung recovery and the bridge to the transplantation is prolonged. To address this issue, a dual-lumen, single venovenous cannula was introduced. Here, by insertion of one single catheter in one target vessel, in a majority of cases in the right internal jugular vein, satisfactory oxygenation of the patient is achieved. In this form, the instituted VV-ECMO enables patient mobility, better physical rehabilitation and facilitates pulmonary extubation and toilet. However, relatively early, after the first short-term reports were published, a relatively high complication rate became evident. In the recent literature, the complication rate using actual commercially available double-lumen venovenous cannula ranges between 5 and 30%. These cases were mostly conjoined to the implantation phase or the early postoperative phase and vary between right heart perforation to migration of the cannula. This review focuses on complications allied to commercially available dual-lumen, single, venovenous cannula implantation, pointing out the critical segments of the implantation process and analyzing the structure of the device.

An activator/repressor dual system allows tight tetracycline-regulated gene expression in budding yeast

We have developed an activator/repressor expression system for budding yeast in which tetracyclines control in opposite ways the ability of tetR-based activator and repressor molecules to bind tetO promoters. This combination allows tight expression of tetO-driven genes, both in a direct (tetracycline-repressible) and reverse (tetracycline-inducible) dual system. Ssn6 and Tup1, that are components of a general repressor complex in yeast, have been tested for their repressing properties in the dual system, using lacZ and CLN2 as reporter genes. Ssn6 gives better results and allows complete switching-off of the regulated genes, although increasing the levels of the Tup1-based repressor by expressing it from a stronger promoter improves repressing efficiency of the latter. Effector-mediated shifts between expression and non-expression conditions are rapid. The dual system here described may be useful for the functional analysis of essential genes whose conditional expression can be tightly controlled by tetracyclines.

The membrane-permeable calmodulin inhibitors (W-7/W-13) bind to membranes changing the electrostatic surface potential. Dual effect of W-13 on EGFR activation

Membrane-permeable calmodulin inhibitors, such as the napthalenesulfonamide derivatives W-7/W-13, trifluoperazine, and calmidazolium, are used widely to investigate the role of calcium/calmodulin (Ca2+/CaM) in living cells. If two chemically different inhibitors (e.g. W-7 and trifluoperazine) produce similar effects, investigators often assume the effects are due to CaM inhibition. Zeta potential measurements, however, show that these amphipathic weak bases bind to phospholipid vesicles at the same concentrations as they inhibit Ca 2 /CaM; this suggests that they also bind to the inner leaflet of the plasma membrane, reducing its negative electrostatic surface potential. This change will cause electrostatically bound clusters of basic residues on peripheral (e.g. Src and K-Ras4B) and integral (e.g. epidermal growth factor receptor (EGFR)) proteins to translocate from the membrane to the cytoplasm. We measured inhibitor-mediated translocation of a simple basic peptide corresponding to the calmodulin-binding juxtamembrane region of the EGFR on model membranes; W-7/W-13 causes translocation of this peptide from membrane to solution, suggesting that caution must be exercised when interpreting the results obtained with these inhibitors in living cells. We present evidence that they exert dual effects on autophosphorylation of EGFR;W-13 inhibits epidermal growth factordependent EGFR autophosphorylation under different experimental conditions, but in the absence of epidermal growth factor, W-13 stimulates autophosphorylation of the receptor in four different cell types. Our interpretation is that the former effect is due toW-13inhibition of Ca 2 /CaM, but thelatter results could be due to binding of W-13 to the plasma membrane.

Health-related quality of life in patients with dual diagnosis: clinical correlates

Background: Although the studies published so far have found an affectation in the Health Related Quality of Life (HRQOL) in both psychiatric and substance use dependence disorders, very few studies have applied HRQOL as an assessment measure in patients suffering both comorbid conditions, or Dual Diagnosis. The aim of the current study was to assess HRQOL in a group of patients with Dual Diagnosis compared to two other non-comorbid groups and to determine what clinical factors are related to HRQOL. Methods: Cross-sectional assessment of three experimental groups was made through the Short Form 36 Item Health Survey (SF-36). The sample consisted of a group with Dual Diagnosis (DD; N=35), one with Severe Mental Illness alone (SMI; N=35) and another one with Substance Use Dependence alone (SUD; N=35). The sample was composed only by males. To assess the clinical correlates of SF-36 HRQOL, lineal regression analyses were carried out. Results: The DD group showed lower scores in most of the subscales, and in the mental health domain. The group with SUD showed in general a better state in the HRQOL while the group with SMI held an intermediate position with respect to the other two groups. Daily medication, suicidal attempts and daily number of coffees were significantly associated to HRQOL, especially in the DD group. Conclusions: The DD group showed lower self-reported mental health quality of life. Assessment of HRQOL in dual patients allows to identify specific needs in this population, and may help to establish therapeutic goals to improve interventions.

Los nuevos sentidos de la tarea de enseñar. Más allá de la dicotomía 'enseñar vs asistir'

La escuela ha estado siendo objeto de un conjunto de demandas para que se hiciera cargo de «todas» las problemáticas de «la» infancia. Este comienzo de siglo nos muestra, con inusitada crudeza, que la única institución pública hasta hoy entronizada por la política social para la educación de las jóvenes generaciones, la escuela, no es suficiente para dar cauce a las múltiples demandas emergentes. Se trata, por tanto, de que la escuela re-centre su función, poniendo coto a un exceso de acumulación de funciones, que, en realidad, pretende ocultar los nuevos designios de la globalización para la escuela pública: su desaparición como instancia democrática y democratizadora en la tramitación de las herencias culturales. El mundo ha cambiado. También el de los niños. La noción misma de sistema que se emplea: un único orden posible para encauzar a «la» infancia, se transforma en el principal obstáculo epistemológico para pensar nuevas maneras de sostener la responsabilidad pública ante las nuevas generaciones. Se trata de realizar un esfuerzo de invención para un siglo nuevo. Podríamos pensar, por ejemplo, en cómo dar soporte a los niños y a los adolescentes para que puedan mantener con éxito su escolaridad, y acceder a lo social en sentido amplio y plural. Tal vez pase por otorgarles estatuto de sujetos de derecho, con quienes es posible convenir propuestas, propulsar proyectos, discutir alternativas. La educación social puede aquí iniciar su andadura. Podríamos pensar también en cómo dar soporte a la escuela para que re-centre su función en la transmisión de los valiosos legados culturales y trabaje en red con otras instituciones, para que niños y adolescentes puedan realizar sus experiencias de movilidad y confrontación. En suma, se trata de apostar porque la educación recupere, ante los procesos de banalización y vaciamiento culturales, la transmisión como polea social y cultural que articule a los jóvenes con el mundo.

Reproducibility of Vertebral Fracture Assessment Readings From Dual-energy X-ray Absorptiometry in Both a Population-based and Clinical Cohort: Cohen's and Uniform Kappa.

Vertebral fracture assessments (VFAs) using dual-energy X-ray absorptiometry increase vertebral fracture detection in clinical practice and are highly reproducible. Measures of reproducibility are dependent on the frequency and distribution of the event. The aim of this study was to compare 2 reproducibility measures, reliability and agreement, in VFA readings in both a population-based and a clinical cohort. We measured agreement and reliability by uniform kappa and Cohen's kappa for vertebral reading and fracture identification: 360 VFAs from a population-based cohort and 85 from a clinical cohort. In the population-based cohort, 12% of vertebrae were unreadable. Vertebral fracture prevalence ranged from 3% to 4%. Inter-reader and intrareader reliability with Cohen's kappa was fair to good (0.35-0.71 and 0.36-0.74, respectively), with good inter-reader and intrareader agreement by uniform kappa (0.74-0.98 and 0.76-0.99, respectively). In the clinical cohort, 15% of vertebrae were unreadable, and vertebral fracture prevalence ranged from 7.6% to 8.1%. Inter-reader reliability was moderate to good (0.43-0.71), and the agreement was good (0.68-0.91). In clinical situations, the levels of reproducibility measured by the 2 kappa statistics are concordant, so that either could be used to measure agreement and reliability. However, if events are rare, as in a population-based cohort, we recommend evaluating reproducibility using the uniform kappa, as Cohen's kappa may be less accurate.

Counter-propagating dual-trap optical tweezers based on linear momentum conservation

We present a dual-trap optical tweezers setup which directly measures forces using linear momentum conservation. The setup uses a counter-propagating geometry, which allows momentum measurement on each beam separately. The experimental advantages of this setup include low drift due to all-optical manipulation, and a robust calibration (independent of the features of the trapped object or buffer medium) due to the force measurement method. Although this design does not attain the high-resolution of some co-propagating setups, we show that it can be used to perform different single molecule measurements: fluctuation-based molecular stiffness characterization at different forces and hopping experiments on molecular hairpins. Remarkably, in our setup it is possible to manipulate very short tethers (such as molecular hairpins with short handles) down to the limit where beads are almost in contact. The setup is used to illustrate a novel method for measuring the stiffness of optical traps and tethers on the basis of equilibrium force fluctuations, i.e., without the need of measuring the force vs molecular extension curve. This method is of general interest for dual trap optical tweezers setups and can be extended to setups which do not directly measure forces.

Force Spectroscopy with Dual-Trap Optical Tweezers: Molecular Stiffness Measurements and Coupled Fluctuations Analysis

ABSTRACT Dual-trap optical tweezers are often used in high-resolution measurements in single-molecule biophysics. Such measurements can be hindered by the presence of extraneous noise sources, the most prominent of which is the coupling of fluctuations along different spatial directions, which may affect any optical tweezers setup. In this article, we analyze, both from the theoretical and the experimental points of view, the most common source for these couplings in dual-trap optical-tweezers setups: the misalignment of traps and tether. We give criteria to distinguish different kinds of misalignment, to estimate their quantitative relevance and to include them in the data analysis. The experimental data is obtained in a, to our knowledge, novel dual-trap optical-tweezers setup that directly measures forces. In the case in which misalignment is negligible, we provide a method to measure the stiffness of traps and tether based on variance analysis. This method can be seen as a calibration technique valid beyond the linear trap region. Our analysis is then employed to measure the persistence length of dsDNA tethers of three different lengths spanning two orders of magnitude. The effective persistence length of such tethers is shown to decrease with the contour length, in accordance with previous studies.

Mueller matrix microscope with a dual continuous rotating compensator setup and digital demodulation

In this paper we describe a new Mueller matrix (MM) microscope that generalizes and makes quantitative the polarized light microscopy technique. In this instrument all the elements of the MU are simultaneously determined from the analysis in the frequency domain of the time-dependent intensity of the light beam at every pixel of the camera. The variations in intensity are created by the two compensators continuously rotating at different angular frequencies. A typical measurement is completed in a little over one minute and it can be applied to any visible wavelength. Some examples are presented to demonstrate the capabilities of the instrument.

A probable dual mode of action for both L- and D-lactate neuroprotection in cerebral ischemia.

Lactate has been shown to offer neuroprotection in several pathologic conditions. This beneficial effect has been attributed to its use as an alternative energy substrate. However, recent description of the expression of the HCA1 receptor for lactate in the central nervous system calls for reassessment of the mechanism by which lactate exerts its neuroprotective effects. Here, we show that HCA1 receptor expression is enhanced 24 hours after reperfusion in an middle cerebral artery occlusion stroke model, in the ischemic cortex. Interestingly, intravenous injection of L-lactate at reperfusion led to further enhancement of HCA1 receptor expression in the cortex and striatum. Using an in vitro oxygen-glucose deprivation model, we show that the HCA1 receptor agonist 3,5-dihydroxybenzoic acid reduces cell death. We also observed that D-lactate, a reputedly non-metabolizable substrate but partial HCA1 receptor agonist, also provided neuroprotection in both in vitro and in vivo ischemia models. Quite unexpectedly, we show D-lactate to be partly extracted and oxidized by the rodent brain. Finally, pyruvate offered neuroprotection in vitro whereas acetate was ineffective. Our data suggest that L- and D-lactate offer neuroprotection in ischemia most likely by acting as both an HCA1 receptor agonist for non-astrocytic (most likely neuronal) cells as well as an energy substrate.

Dual role of LldR in regulation of the lldPRD operon, involved in l-Lactate metabolism in Escherichia coli.

The lldPRD operon of Escherichia coli, involved in L-lactate metabolism, is induced by growth in this compound. We experimentally identified that this system is transcribed from a single promoter with an initiation site located 110 nucleotides upstream of the ATG start codon. On the basis of computational data, it had been proposed that LldR and its homologue PdhR act as regulators of the lldPRD operon. Nevertheless, no experimental data on the function of these regulators have been reported so far. Here we show that induction of an lldP-lacZ fusion by L-lactate is lost in an lldR mutant, indicating the role of LldR in this induction. Expression analysis of this construct in a pdhR mutant ruled out the participation of PdhR in the control of lldPRD. Gel shift experiments showed that LldR binds to two operator sites, O1 (positions 105 to 89) and O2 (positions 22 to 38), with O1 being filled at a lower concentration of LldR. L-Lactate induced a conformational change in LldR that did not modify its DNA binding activity. Mutations in O1 and O2 enhanced the basal transcriptional level. However, only mutations in O1 abolished induction by L-lactate. Mutants with a change in helical phasing between O1 and O2 behaved like O2 mutants. These results were consistent with the hypothesis that LldR has a dual role, acting as a repressor or an activator of lldPRD. We propose that in the absence of L-lactate, LldR binds to both O1 and O2, probably leading to DNA looping and the repression of transcription. Binding of L-lactate to LldR promotes a conformational change that may disrupt the DNA loop, allowing the formation of the transcription open complex.