DNA transport by a micromachined Brownian ratchet device

We have micromachined a silicon-chip device that transports DNA with a Brownian ratchet that rectifies the Brownian motion of microscopic particles. Transport properties for a DNA 50mer agree with theoretical predictions, and the DNA diffusion constant agrees with previous experiments. This type of micromachine could provide a generic pump or separation component for DNA or other charged species as part of a microscale lab-on-a-chip. A device with reduced feature size could produce a size-based separation of DNA molecules, with applications including the detection of single nucleotide polymorphisms.Comment: Latex: 8 pages, 4 figure

Early and late improvement of global and regional left ventricular function after transcatheter aortic valve implantation in patients with severe aortic stenosis: an echocardiographic study.

The recent development of transcatheter aortic valve implantation (TAVI) for severe aortic stenosis (AS) treatment offers a viable option for high-risk patient categories. Our aim is to evaluate whether 2D strain and strain rate can detect subtle improvement in global and regional LV systolic function immediately after TAVI. 2D conventional and 2D strain (speckle analysis) echocardiography was performed before, at discharge and after three months in thirty three patients with severe AS. After TAVI, we assessed by conventional echocardiography an immediate reduction of transaortic peak pressure gradient (p<0.0001), of mean pressure gradient (p<0.0001) and a concomitant increase in aortic valve area (AVA: 1.08±0.31 cm(2)/m(2); p<0.0001). 2D longitudinal systolic strain showed a significant improvement in all patients, both at septal and lateral level, as early as 72 h after procedure (septal: -14.2±5.1 vs -16.7±3.7%, p<0.001; lateral: -9.4±3.9 vs -13.1±4.5%, p<0.001; respectively) and continued at 3 months follow-up (septal: -18.1±4.6%, p<0.0001; lateral: -14.8±4.4%, p<0.0001; respectively). Conventional echocardiography after TAVI proved a significant reduction of LV end-systolic volume and of LV mass with a mild improvement of LV ejection fraction (EF) (51.2±11.8 vs 52.9±6.4%; p<0.02) only after three months. 2D strain seems to be able to detect subtle changes in LV systolic function occurring early and late after TAVI in severe AS, while all conventional echo parameters seem to be less effective for this purpose. Further investigations are needed to prove the real prognostic impact of these echocardiographic findings

Comparison between Airway Responses to High versus Low Molecular Weight Compounds in Occupational Asthma

Occupational asthma (OA) is a heterogeneous disease, and the characteristics of the sensitizer responsible for OA may induce different clinical, functional, and biological manifestations. We examined the characteristics of 74 patients with OA induced by low molecular weight compounds (LMWC) or by high molecular weight compounds (HMWC) and diagnosed by specific inhalation challenge (SIC). Patients with OA induced by LMWC had a longer occupational exposure before the beginning of symptoms, a lower sputum eosinophilia, and a higher prevalence of late airway response (LAR), in comparison with patients with OA induced by HMWC. Pulmonary function tended to be poorer and atopy tended to be less frequent in LMWC-induced OA than in HMWC-induced OA. These data confirm and extend previous observations showing that the characteristics of the specific sensitizer inducing OA may determine different clinical, functional, and biological features, probably related to the difference pathogenetic mechanisms underlying these different types of OA

Soliton ratchets

The mechanism underlying the soliton ratchet, both in absence and in presence of noise, is investigated. We show the existence of an asymmetric internal mode on the soliton profile which couples, trough the damping in the system, to the soliton translational mode. Effective soliton transport is achieved when the internal mode and the external force are phase locked. We use as working model a generalized double sine-Gordon equation. The phenomenon is expected to be valid for generic soliton systems.Comment: 4 pages, 4 figure

BIOHYBRID – Biohybrid templates for peripheral nerve regeneration

[Excerpt] Peripheral nerve injuries represent a major cause for morbidity and disability in affected patients and cause substantial costs for society in a global perspective. It has been estimated that peripheral nerve injuries affect 2.8% of trauma patients,many of whom acquire life-long disability (Noble et al., 1998). With respect to an incidence of nerve injuries of 13.9/100,000 inhabitants per year (Asplund et al., 2009) and the number of inhabitants in the EU (495,000,000 inhabitants in 2007), the number of peripheral nerve injuries requiring repair and reconstruction, excluding nerve injuries by amputations, may be 70,000 annually only in EU countries. Related to peripheral nerve injuries, the costs for society are substantial and consist of direct (costs for surgery, outpatient visits and rehabilitation) and indirect (lost production) costs. Individual median and ulnar nerve injuries in the forearm have total costs of EUR 51,000 and 31,000, respectively, where around 85% of the costs consist of loss of production (Rosberg et al., 2005), still excluding costs for adjusted quality of life ( Eriksson et al., 2011) . Thus, one may estimate that the annual costs only in the EU may be as high as EUR 2.2 billion, indicating that improved treatment strategies for peripheral nerve injuries may not only improve the situation for patients, but may also significantly reduce costs for society. [...](undefined

Disorder Induced Diffusive Transport In Ratchets

The effects of quenched disorder on the overdamped motion of a driven particle on a periodic, asymmetric potential is studied. While for the unperturbed potential the transport is due to a regular drift, the quenched disorder induces a significant additional chaotic ``diffusive'' motion. The spatio-temporal evolution of the statistical ensemble is well described by a Gaussian distribution, implying a chaotic transport in the presence of quenched disorder.Comment: 10 pages, 4 EPS figures; submitted to Phys. Rev. Letter

Severe Aortic Stenosis and Myocardial Function: Diagnostic and Prognostic Usefulness of Ultrasonic Integrated Backscatter Analysis

Background— The aim of this study was to assess the myocardial reflectivity pattern in severe aortic valve stenosis through the use of integrated backscatter (IBS) analysis. Patients with aortic stenosis (AS) were carefully selected in the Department of Cardiology. Methods and Results— Thirty-five subjects (AS: valve orifice ≤1 cm2; 12 female; mean age, 71.8±6.2 years) and 25 healthy subjects were studied. All subjects of the study had conventional 2D-Doppler echocardiography and IBS. Backscatter signal was sampled at the septum and posterior wall levels. Patients with AS were divided into 2 groups: 16 patients with initial signs of congestive heart failure and a depressed left ventricular systolic function (DSF) (ejection fraction [EF] range, 35% to 50%) and 19 asymptomatic patients with normal left ventricular systolic function (NSF) (EF >50%). Myocardial echo intensity (pericardium related) was significantly higher at the septum and posterior wall levels in DSF than in NSF and in control subjects. IBS variation, as an expression of variation of the signal, appeared to be significantly lower in AS with DSF than in NSF and in control subjects, at both the septum and posterior wall levels. Patients with DSF underwent aortic valve replacement, and, during surgical intervention, a septal myocardial biopsy was made for evaluation of myocardium/fibrosis ratio. Abnormally increased echo intensity was detected in left ventricular pressure overload by severe aortic stenosis and correlated with increase of myocardial collagen content (operating biopsy). Conclusions— One year after aortic valve replacement, we observed a significant reduction of left ventricular mass, and, only if pericardial indexed IBS value (reduction of interstitial fibrosis) decreased, it was possible to observe an improvement of EF and of IBS variation