Platinum-gold nanoclusters as catalyst for direct methanol fuel cells

Nanosized platinum-gold alloys clusters have been deposited on gas diffusion electrode by sputter deposition. The deposits were characterized by FE-SEM, TEM and XPS in order to verify the formation of alloy nanoparticles and to study the influence of deposition technique on the nanomorphology. The deposition by sputtering process allowed a uniform distribution of metal particles on porous surface of carbon supports. Typical island growth mode was observed with the formation of a dispersed metal nanoclusters (mean size about 5 nm). Cyclic voltammetry was used to determine the electrochemical active surface and the electrocatalytic performance of the PtAu electrocatalysts for methanol oxidation reaction. The data were re-calculated in the form of mass specific activity (MSA). The sputter-catalyzed electrodes showed higher performance and stability compared to commercial catalysts.

Emulsion polymerization of vinyl acetate: safe optimization of a hazardous complex process

Fast and exothermic discontinuous emulsion polymerization processes are particularly difficult to optimize from both safety and productivity point of view because of the occurrence of side undesired reactions (e.g. chain transfer to monomer, backbiting, propagation of tertiary radicals, termination by disproportion, etc.) and the hazards of boiling phenomena and stable foam formation under atmospheric pressure. Moreover, the relevant number of loading, heating and cooling steps, required before starting the monomer addition (that is, the desired reaction), makes a strict product quality reproducibility very difficult to obtain. Under these operating conditions, it is necessary to employ a suitable combined theoretical and experimental procedure able to detect the optimum process dosing time at both the laboratory and the industrial scale. In this work, it is shown how to use the topological criterion theory together with proper adiabatic calorimeter and RC1 experimental data to safely optimize the synthesis of polyvinyl acetate through the radical emulsion polymerization of vinyl acetate by the means of an indirectly cooled isoperibolic semibatch reactor.

A mild neurofibromatosis type 1 phenotype produced by the combination of the benign nature of a leaky NF1-splice mutation and the presence of a complex mosaicism

Here we analyze the genetic and molecular basis responsible for a very benign phenotype observed in an NF1 patient. Quantification of cells carrying the NF1 mutation in different samples derived from the three embryonic layers revealed mosaicism. Furthermore, the construction of a minigene with patient's mutation (c.3198 - 314G>A) confirmed its benign nature due to the leakiness of the splicing mechanism that generated a proportion of correctly spliced transcripts. Hence, we concluded that the mild phenotype observed in this patient is the result of the presence of mosaicism together with the benign nature of a leaky NF1-splice mutation. Finally, with the aim of developing a personalized therapeutic approach for this patient, we demonstrated correction of the splicing defect by using specific antisense morpholino oligomers. Our results provide an example of the molecular complexity behind disease phenotypes and highlight the importance of using comprehensive genetic approaches to better assess phenotype-genotype correlations.

A mild neurofibromatosis type 1 phenotype produced by the combination of the benign nature of a leaky NF1-splice mutation and the presence of a complex mosaicism

Here we analyze the genetic and molecular basis responsible for a very benign phenotype observed in an NF1 patient. Quantification of cells carrying the NF1 mutation in different samples derived from the three embryonic layers revealed mosaicism. Furthermore, the construction of a minigene with patient's mutation (c.3198 - 314G>A) confirmed its benign nature due to the leakiness of the splicing mechanism that generated a proportion of correctly spliced transcripts. Hence, we concluded that the mild phenotype observed in this patient is the result of the presence of mosaicism together with the benign nature of a leaky NF1-splice mutation. Finally, with the aim of developing a personalized therapeutic approach for this patient, we demonstrated correction of the splicing defect by using specific antisense morpholino oligomers. Our results provide an example of the molecular complexity behind disease phenotypes and highlight the importance of using comprehensive genetic approaches to better assess phenotype-genotype correlations.

Carbon nanotube films as a platform to transduce molecular recognition events in metalloporphyrins

Porphyrins have been widely used for many years as functional materials for chemical sensors. Their outstanding chemical features are balanced by some restrictions in terms of transduction techniques. In particular, porphyrin layers are barely conductive, with the consequence that the fabrication of porphyrin based chemiresistors is not possible, except in few rare cases. On the other hand, carbon nanotubes (CNTs) have superior electric properties ranging from metallic to semiconductor in character. Although the conductivity of CNTs is very sensitive to adsorbed molecules, it should be considered that the adsorption onto carbon structures is also scarcely selective and cannot be modified unless other molecular recognition systems are coupled with the CNTs. Following this approach, in this paper we investigated the sensing properties of hybrid CNT-porphyrin films to explore the possibility of transducing the adsorption events occurring in a porphyrin layer into resistance changes of the CNT layers. The results obtained indicate that the presence of the porphyrin films increases the sensitivity of the electric resistance of the CNTs to the concentration of volatile compounds. This enhancement is probably due to the catalytic effect of the metalloporphyrin in conveying the charge transfer from the adsorbate molecule to the CNTs substrate. This property of metalloporphyrins may introduce a further differentiation between porphyrin based sensors that could be positively utilized in sensor array configurations.

Mosaic type-1 NF1 microdeletions as a cause of both generalized and segmental neurofibromatosis type-1 (NF1)

Mosaicism is an important feature of type-1 neurofibromatosis (NF1) on account of its impact upon both clinical manifestations and transmission risk. Using FISH and MLPA to screen 3500 NF1 patients, we identified 146 individuals harboring gross NF1 deletions, 14 of whom (9.6%) displayed somatic mosaicism. The high rate of mosaicism in patients with NF1 deletions supports the postulated idea of a direct relationship between the high new mutation rate in this cancer predisposition syndrome and the frequency of mosaicism. Seven of the 14 mosaic NF1 deletions were type-2, whereas four were putatively type-1, and three were atypical. Two of the four probable type-1 deletions were confirmed as such by breakpoint-spanning PCR or SNP analysis. Both deletions were associated with a generalized manifestation of NF1. Independently, we identified a third patient with a mosaic type-1 NF1 deletion who exhibited segmental NF1. Together, these three cases constitute the first proven mosaic type-1 deletions so far reported. In two of these three mosaic type-1 deletions, the breakpoints were located within PRS1 and PRS2, previously identified as hotspots for nonallelic homologous recombination (NAHR) during meiosis. Hence, NAHR within PRS1 and PRS2 is not confined to meiosis but may also occur during postzygotic mitotic cell cycles.

Development of the Fibromyalgia Burden Assessment: measuring the multifaceted burden of fibromyalgia

OBJECTIVES

To develop a questionnaire assessing the burden of fibromyalgia's impacts on patients' lives.

METHODS

A literature review was conducted to identify impacts of fibromyalgia and their consequences on patients' lives. Exploratory interviews were performed with 15 fibromyalgia patients in France, Germany and Spain. Using patients' wording, items were generated simultaneously in French, German, Spanish, and UK English. Relevance and comprehension of the resulting questionnaire versions were tested with 21 additional fibromyalgia patients; questionnaires were revised accordingly.

RESULTS

Three domains, Burden associated with the impacts of fibromyalgia, Symptoms and Influencing factors, were identified from the literature review. Following patient interviews, the burden domain was further divided based on the nature of the impact: Pain, Physical impact (including tiredness, sleep problems and other symptoms), Activities of Daily Living impact (including autonomy and coping), Social and Family Life impact, Work, Studies and Personal Finances impact, Psychological impact (including cognitive impact), and Relationship to Medicine and Disease. The resulting test versions of the questionnaire contained 79 items. Comprehension tests identified problematic items and cultural differences and suggested deletions or rewording. After revision and linguistic harmonization, the pilot version of the questionnaire contained 62 items divided into 7 sections, and was named Fibromyalgia Burden Assessment (FMBA©).

CONCLUSIONS

The FMBA is a self-reported questionnaire allowing the assessment and a better understanding of the impacts of fibromyalgia and the burden associated with these on patients' daily lives. It is available in UK English, French, German and Spanish. Its scoring and validation remain to be undertaken.

Metal-modified and vertically aligned carbon nanotube sensors array for landfill gas monitoring applications

Vertically aligned carbon nanotube (CNT) layers were synthesized on Fe-coated low-cost alumina substrates using radio-frequency plasma enhanced chemical vapour deposition (RF-PECVD) technology. A miniaturized CNT-based gas sensor array was developed for monitoring landfill gas (LFG) at a temperature of 150 degrees C. The sensor array was composed of 4 sensing elements with unmodified CNT, and CNT loaded with 5 nm nominally thick sputtered nanoclusters of platinum (Pt), ruthenium (Ru) and silver (Ag). Chemical analysis of multicomponent gas mixtures constituted of CO(2), CH(4), H(2), NH(3), CO and NO(2) has been performed by the array sensor responses and pattern recognition based on principal component analysis (PCA). The PCA results demonstrate that the metal-decorated and vertically aligned CNT sensor array is able to discriminate the NO(2) presence in the multicomponent mixture LFG. The NO(2) gas detection in the mixture LFG was proved to be very sensitive, e.g.: the CNT:Ru sensor shows a relative change in the resistance of 1.50% and 0.55% for NO(2) concentrations of 3.3 ppm and 330 ppb dispersed in the LFG, respectively, with a wide NO(2) gas concentration range measured from 0.33 to 3.3 ppm, at the sensor temperature of 150 degrees C. The morphology and structure of the CNT networks have been characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Raman spectroscopy. A forest-like nanostructure of vertically aligned CNT bundles in the multi-walled form appeared with a height of about 10 microm and a single-tube diameter varying in the range of 5-35 nm. The intensity ratio of the Raman spectroscopy D-peak and G-peak indicates the presence of disorder and defects in the CNT networks. The size of the metal (Pt, Ru, Ag) nanoclusters decorating the CNT top surface varies in the range of 5-50 nm. Functional characterization based on electrical charge transfer sensing mechanisms in the metal-modified CNT-chemoresistor array demonstrates high sensitivity by providing minimal sub-ppm level detection, e.g., download up to 100 ppb NO(2), at the sensor temperature of 150 degrees C. The gas sensitivity of the CNT sensor array depends on operating temperature, showing a lower optimal temperature of maximum sensitivity for the metal-decorated CNT sensors compared to unmodified CNT sensors. Results indicate that the recovery mechanisms in the CNT chemiresistors can be altered by a rapid heating pulse from room temperature to about 110 degrees C. A comparison of the NO(2) gas sensitivity for the chemiresistors based on disorderly networked CNTs and vertically aligned CNTs is also reported. Cross-sensitivity towards relative humidity of the CNT sensors array is investigated. Finally, the sensing properties of the metal-decorated and vertically aligned CNT sensor arrays are promising to monitor gas events in the LFG for practical applications with low power consumption and moderate sensor temperature.

Integrative genomic analyses of neurofibromatosis tumours identify SOX9 as a biomarker and survival gene

Understanding the biological pathways critical for common neurofibromatosis type 1 (NF1) peripheral nerve tumours is essential, as there is a lack of tumour biomarkers, prognostic factors and therapeutics. We used gene expression profiling to define transcriptional changes between primary normal Schwann cells (n = 10), NF1-derived primary benign neurofibroma Schwann cells (NFSCs) (n = 22), malignant peripheral nerve sheath tumour (MPNST) cell lines (n = 13), benign neurofibromas (NF) (n = 26) and MPNST (n = 6). Dermal and plexiform NFs were indistinguishable. A prominent theme in the analysis was aberrant differentiation. NFs repressed gene programs normally active in Schwann cell precursors and immature Schwann cells. MPNST signatures strongly differed; genes up-regulated in sarcomas were significantly enriched for genes activated in neural crest cells. We validated the differential expression of 82 genes including the neural crest transcription factor SOX9 and SOX9 predicted targets. SOX9 immunoreactivity was robust in NF and MPSNT tissue sections and targeting SOX9 – strongly expressed in NF1-related tumours – caused MPNST cell death. SOX9 is a biomarker of NF and MPNST, and possibly a therapeutic target in NF1.

Follow-up of adolescents with diabetes after transition from paediatric to adult care: results of a 10-year prospective study

OBJECTIVE

Our main objective in this study was to identify the type of clinical care received by young type 1 diabetic patients who have made the transition from paediatric to adult care, and to assess the metabolic status of long-term treatment after the transition.

METHODS

A standardized questionnaire was used prospectively to follow 99 patients with type 1 diabetes mellitus after their transition to adult care. This survey was done once a year, from 1998 to 2008.

RESULTS

Directly after transition from paediatric care 38.4% of patients were found at specialised outpatient units; whereas 41.1% received care at a diabetes centre and 20.5% were monitored by general practitioners or specialists in internal medicine. Five-year results showed that 25.0% had continued to visit an outpatient unit; 41.7% were still visiting a diabetes centre; and 33.3% had remained in the care of general practitioners or internal specialists. We observed a trend showing slight improvements in the HbA1c values over time, however no major changes in metabolic control were observed after transition.

CONCLUSIONS

Transition marks a critical phase for young, diabetic patients as they may frequently switch from one physician or centre to another. The individual optimization of therapy, established during paediatric care, provides the decisive groundwork for disease control in young adults.

Modulation of aberrant NF1 pre-mRNA splicing by kinetin treatment

Neurofibromatosis type 1 is one of the most common neurocutaneous autosomal dominant disorders. It is caused by mutations in the neurofibromatosis type 1 (NF1) gene and approximately 30-40% of them affect the correct splicing of NF1 pre-mRNA. In this report, we evaluate the effect of five different drugs, previously found to modify splicing in several genetic disorders, on the splicing of mutated NF1 alleles. For this purpose, cell lines derived from patients bearing 19 different NF1-splicing defects were used. Our results showed that kinetin partially corrects the splicing defect in four of the studied mutations (c.910C>T, c.3113G>A, c.6724C>T and c.6791dupA). Our study is a valuable contribution to the field because it identifies new exon-skipping events that can be reversed by kinetin treatment and provides new information about kinetin splicing modulation. However, owing to the nature of mutations in our patients, kinetin treatment could not be used as a therapeutic agent in these cases.

Bevacizumab-Related Osteneocrosis of the Jaw

We describe a case of jaw bone necrosis after a lung adenocarcinoma bone metastasis, treated the first time in 2004 by means of pneumonectomy and lymph node ablation. One week after a dental extraction, the patient experienced pain in the mandibular region, in conjunction with alveolar bone exposure. Treatment with amoxicillin and clavulanate every 12 hours for 15 days and 0.2% chlorhexidine rinses was administered and there was a remission of infective complications, but not the closure of the exposed alveolar bone. Only at this time did the patient refer that he was treated with bevacizumab therapy immediately after the extraction. A preventive dental assessment of patients scheduled for bevacizumab therapy should be useful as for the zoledronic acid therapy. Dental surgery procedures for patients during bevacizumab therapy should be carefully evaluated and considered as the last choice, to reduce all possible risks and prevent complications.

Antisense therapeutics for neurofibromatosis type 1 caused by deep intronic mutations

Neurofibromatosis type 1 (NF1) is an autosomal dominant disorder affecting 1:3,500 individuals. Disease expression is highly variable and complications are diverse. However, currently there is no specific treatment for the disease. NF1 is caused by mutations in the NF1 gene, approximately 2.1% of constitutional mutations identified in our population are deep intronic mutations producing the insertion of a cryptic exon into the mature mRNA. We used antisense morpholino oligomers (AMOs) to restore normal splicing in primary fibroblast and lymphocyte cell lines derived from six NF1 patients bearing three deep intronic mutations in the NF1 gene (c.288+2025T>G, c.5749+332A>G, and c.7908-321C>G). AMOs were designed to target the newly created 5' splice sites to prevent the incorporation of cryptic exons. Our results demonstrate that AMO treatment effectively restored normal NF1 splicing at the mRNA level for the three mutations studied in the different cell lines analyzed. We also found that AMOs had a rapid effect that lasted for several days, acting in a sequence-specific manner and interfering with the splicing mechanism. Finally, to test whether the correction of aberrant NF1 splicing also restored neurofibromin function to wild-type levels, we measured the amount of Ras-GTP after AMO treatment in primary fibroblasts. The results clearly show an AMO-dependent decrease in Ras-GTP levels, which is consistent with the restoration of neurofibromin function. To our knowledge this is the first time that an antisense technique has been used successfully to correct NF1 mutations opening the possibility of a therapeutic strategy for this type of mutation not only for NF1 but for other genetic disorders.

The Alpha Project: a model system for systems biology research

One goal of systems biology is to understand how genome-encoded parts interact to produce quantitative phenotypes. The Alpha Project is a medium-scale, interdisciplinary systems biology effort that aims to achieve this goal by understanding fundamental quantitative behaviours of a prototypic signal transduction pathway, the yeast pheromone response system from Saccharomyces cerevisiae. The Alpha Project distinguishes itself from many other systems biology projects by studying a tightly bounded and well-characterised system that is easily modified by genetic means, and by focusing on deep understanding of a discrete number of important and accessible quantitative behaviours. During the project, the authors have developed tools to measure the appropriate data and develop models at appropriate levels of detail to study a number of these quantitative behaviours. The authors have also developed transportable experimental tools and conceptual frameworks for understanding other signalling systems. In particular, the authors have begun to interpret system behaviours and their underlying molecular mechanisms through the lens of information transmission, a principal function of signalling systems. The Alpha Project demonstrates that interdisciplinary studies that identify key quantitative behaviours and measure important quantities, in the context of well-articulated abstractions of system function and appropriate analytical frameworks, can lead to deeper biological understanding. The authors' experience may provide a productive template for systems biology investigations of other cellular systems.

Negative feedback that improves information transmission in yeast signalling

Haploid Saccharomyces cerevisiae yeast cells use a prototypic cell signalling system to transmit information about the extracellular concentration of mating pheromone secreted by potential mating partners. The ability of cells to respond distinguishably to different pheromone concentrations depends on how much information about pheromone concentration the system can transmit. Here we show that the mitogen-activated protein kinase Fus3 mediates fast-acting negative feedback that adjusts the dose response of the downstream system response to match the dose response of receptor-ligand binding. This 'dose-response alignment', defined by a linear relationship between receptor occupancy and downstream response, can improve the fidelity of information transmission by making downstream responses corresponding to different receptor occupancies more distinguishable and reducing amplification of stochastic noise during signal transmission. We also show that one target of the feedback is a previously uncharacterized signal-promoting function of the regulator of G-protein signalling protein Sst2. Our work suggests that negative feedback is a general mechanism used in signalling systems to align dose responses and thereby increase the fidelity of information transmission.

Noninvasive ventilation in adult liver transplantation

Noninvasive ventilation (NIV) has proven to be a safe and effective technique in the treatment of respiratory failure complicating various medical and surgical diseases. In recent years, a growing interest has emerged in its adoption for ventilatory assistance in immunocompromised patients, such as those undergoing bone marrow, liver, lung, cardiac, and kidney transplantation. Weaning from the ventilator after liver transplantation can take longer because of unsatisfactory gas exchange during various attempts of T-piece trials. Rapid extubation followed by an immediate NIV application should be considered in this setting to shorten and accelerate the weaning process in those recipients who do not completely fulfill the criteria for safe extubation. By adding the pressure support (PS) mode with a continuous positive end expiratory pressure (PEEP), NIV could prevent the loss of vital capacity and impede severe lung derecruitment following extubation. Clinical experience has shown that properly delivered NIV mostly benefits moderately dyspneic recipients in acute respiratory failure, while it appears less promising and efficient in patients ventilated for extended periods of time. It has proven safe and efficient mainly as (1) a tool to promote an early ventilatory discontinuation and extubation; (2) a prophylactic strategy for preventing postoperative pulmonary complications; and (3) a simple method to start with in cases of acute hypoxic and/or hypercapnic respiratory failure. The improvements in arterial hypoxemia, the decreased ventilatory demand provided with an inspiratory support, as well as the scarcity of hemodynamic repercussions are among the major benefits of this method.

Activated recombinant protein C in septic shock early after liver transplantation: a case report

Severe infectious diseases after liver transplant are associated with high risk of multiorgan failure and mortality. Septic shock is difficult to manage in this setting since it is often unresponsive to conventional aggressive therapy. Adjuvant therapies have been proposed in association with full combination treatment to sustain the failing organs and improve outcomes in severe sepsis. Recombinant human activated protein C drotrecogin alfa, Xigris) has been occasionally administered to treat posttransplant sepsis to modulate and downregulate the complex network of inflammatory and coagulopathic processes. Herein we have reported on a patient who was given drotrecogin alfa 15 days following liver transplant for acute septic shock originating from a nosocomially acquired pneumonia. Recombinant activated drotrecogin alfa, associated with conventional aggressive treatment, was efficacious to revert the life-threatening "slippery slope" of vasoplegia and uncontrolled diffuse inflammation.

Epidural anesthesia and analgesia in liver resection and living donor hepatectomy

Parenteral analgesics are still diffusely administered for postoperative pain after major liver resection, while epidural analgesia is widely criticized because of possible changes in the postoperative coagulation profile. The safety of regional anesthesia in liver resections is based on appropriate timing of needle placement and catheter removal and on the individual's skill in performing both the puncture and the catheterization. In the absence of liver failure or in cases of only moderate hepatic dysfunction, the risk of neurologic complications and spinal hematomas does not appear greater than when an epidural is performed for routine abdominal or thoracic surgery. Various anesthetic strategies have been adopted to prevent bleeding during liver resection, such as fluid restriction, diuretic administration, and vasodilator drugs. Lowering central venous pressure (CVP) seems to play a prominent role in prevention of bleeding since an elevated CVP may be associated with increased blood loss at various phases of liver resection. However, a low CVP may not be tolerated by all patients: intraoperative hemodynamic instability may, in fact, easily ensue because of the cardiovascular depressant effects of anesthetics, surgical blood losses, and manipulation of the inferior vena cava. We suggest combining intraoperative epidural anesthesia with general (light) anesthesia as a useful strategy to keep the CVP low during liver resection without vasodilators or diuretics. Epidural anesthesia does not lead to changes in intravascular volume, but only promotes redistribution of blood, decreasing both venous return and portal vein pressure, thus contributing to reduced hepatic congestion and surgical blood loss.

Loss budget of a setup for measuring mechanical dissipations of silicon wafers between 300 and 4 K

A setup for measuring mechanical losses of silicon wafers has been fully characterized from room temperature to 4 K in the frequency range between 300 Hz and 4 kHz: it consists of silicon wafers with nodal suspension and capacitive and optical vibration sensors. Major contributions to mechanical losses are investigated and compared with experimental data scanning the full temperature range; in particular, losses due to the thermoelastic effect and to the wafer clamp are modeled via finite element method analysis; surface losses and gas damping are also estimated. The reproducibility of the measurements of total losses is also discussed and the setup capabilities for measuring additive losses contributed by thin films deposited on the wafers or bonding layers. For instance, assuming that additive losses are due to an 80-nm-thick wafer bond layer with Young modulus about ten times smaller than that of silicon, we achieve a sensitivity to bond losses at the level of 5x10(-3) at 4 K and at about 2 kHz.