Increased flexibility in lab-on-chip design with a polymer patchwork approach

Nanofluidic structures are often the key element of many lab-on-chips for biomedical and environmental applications. The demand for these devices to be able to perform increasingly complex tasks triggers a request for increasing the performance of the fabrication methods. Soft lithography and poly(dimethylsiloxane) (PDMS) have since long been the basic ingredients for producing low-cost, biocompatible and flexible devices, replicating nanostructured masters. However, when the desired functionalities require the fabrication of shallow channels, the \u201croof collapse\u201d phenomenon, that can occur when sealing the replica, can impair the device functionalities. In this study, we demonstrate that a \u201cfocused drop-casting\u201d of h-PDMS (hard PDMS) on nanostructured regions, provides the necessary stiffness to avoid roof collapse, without increasing the probability of deep cracks formation, a drawback that shows up in the peel-off step, when h-PDMS is used all over the device area. With this new approach, we efficiently fabricate working devices with reproducible sub-100 nm structures. We verify the absence of roof collapse and deep cracks by optical microscopy and, in order to assess the advantages that are introduced by the proposed technique, the acquired images are compared with those of cracked devices, whose top layer, of h-PDMS, and with those of collapsed devices, made of standard PDMS. The geometry of the critical regions is studied by atomic force microscopy of their resin casts. The electrical resistance of the nanochannels is measured and shown to be compatible with the estimates that can be obtained from the geometry. The simplicity of the method and its reliability make it suitable for increasing the fabrication yield and reducing the costs of nanofluidic polymeric lab-on-chips

Aneurysms of anomalous splenomesenteric trunk: clinical features and surgical management in two cases

Aneurysms of the splenic artery that anomalously arise from a splenomesenteric trunk are a rarity. Aneurysmal disease of visceral arteries is found in only 0.2% of the general population. The celiac trunk and superior mesenteric artery (SMA) are involved in less than 10% of all visceral aneurysms. Although rupture seems to occur in 20% to 22% of patients, the related mortality rate can rise as high as 100%. Anomalies of the celiac trunk and SMA, more common than previously claimed, include the splenic artery arising from the SMA, which occurs in only 1% of patients. We present two cases of young patients who had 4-cm aneurysms behind the pancreas that involved an anomalous splenic artery. The first patient required dissection of the entire splenopancreatic bloc through a transverse abdominal incision to excise the aneurysm and repair the SMA. The second patient was treated by the classic approach, through a median incision and by entering the mesenteric root. There do not seem to be reports of similar cases, except for two cases of aneurysms involving the celiomesenteric trunk. The cause of these aneurysms can be attributed to mesenchymal alterations during the embryonic formation of aortic collateral branches. A correct surgical approach to splanchnic aneurysms calls for awareness of potential vascular variations of the arteries and their collateral pathways

L'applicazione clinica del trapianto di polmone

Successful lung transplantation has taken longer to develop than other organ transplants. Nevertheless, lung transplantation has now become a viable clinical option for the treatment of irreversibile end-stage respiratory failures. A brief history of lung transplantation is followed by a discussion of the current surgical indications for single and double lung transplants. The criteria for the evaluation and preoperative management of potential candidates are reported. The surgical techniques used for harvesting, preserving and transplanting one or both lungs are then described, including the latest procedure of sequential bilateral lung transplantation. Almost 300 patients have undergone single or double lung transplants all over the world with a survival rate of more than 60%, the earliest patients surviving for over six years. Lung function and exercise tolerance have satisfactorily improved. Despite a number of problems in airway anastomosis and in diagnosing and treating rejection still to be resolved, lung transplantation is rapidly gaining ground worldwide