Systemic and local antibiotic prophylaxis in the prevention of Staphylococcus epidermidis graft infection

BACKGROUND: The aim of the study was to investigate the in vivo efficacy of local and systemic antibiotic prophylaxis in the prevention of Staphylococcus (S.) epidermidis graft infection in a rat model and to evaluate the bacterial adherence to frequently used prosthetic graft materials. METHODS: Graft infections were established in the subcutaneous tissue of 120 male Wistar rats by implantation of Dacron/ePTFE grafts followed by topical inoculation with 2 × 10(7 )CFUs of clinical isolate of methicillin-resistant S. epidermidis. Each of the graft series included a control group, one contaminated group that did not receive any antibiotic prophylaxis, two contaminated groups that received systemic prophylaxis with teicoplanin or levofloxacin and two contaminated groups that received teicoplanin-soaked or levofloxacin-soaked grafts. The grafts were removed 7 days after implantation and evaluated by quantitative culture. RESULTS: There was significant bacterial growth inhibition in the groups given systemic or local prophylaxis (P < 0.05). Methicillin-resistant S. epidermidis had greater affinity to Dacron graft when compared with ePTFE graft in the untreated contaminated groups (P < 0.05). CONCLUSION: The study demonstrated that the usage of systemic or local prophylaxis and preference of ePTFE graft can be useful in reducing the risk of vascular graft infections caused by staphylococcal strains with high levels of resistance

High performance MMICs for automotive radar application at 77 GHz

A set of functions and multifunctions has been developed using 0.25 um HEMT and 0.15 um pseudomorphic HEMT processes for automotive radar application at 77 GHz. The main objective of this work was to appreciate which performances can be reached on these processes for high volume applications. A large number of functions were considered in order to be able to fullfil several radar block diagram requirements (FMCW, pulsed, homodyne, heterodyne...). A set of high performance functions has been realised for frequency generation, transmission and reception circuits

Новеллы законодательства об авторском праве и смежных правах

After investigation of the possible HBT low frequency noise sources and their localization in order to extract a HBT low frequency noise model, the realisation and performances of a S band Voltage Controlled Oscillator (VCO) is reported. This VCO is fully integrated in MMIC technology, and is based on a push-push topology. The circuit is covering 280 MHz tuning range around a centre frequency of 2 GHz with a phase noise of –95 dBc/Hz at 10 KHz offset

New compact power cells for Ku band applications

International audienceThis paper reports on the design of new power cells based on GaAs PHEMT transistors with 0.25μm gate length in MMIC technology. The design starts from a fishbone power cell initially designed by United Monolithic Semiconductors (UMS). This one allows us to validate the elementary transistor model. This model is used for other power cells design as cascode cell

Design of an Integrated Cascode Cell for Compact Ku-Band Power Amplifiers.

International audienceThis paper reports on the design of a new power cell dedicated to Ku-band power amplifier (PA) applications. This cell called '"integrated cascode"' has been designed in order to propose a strong decrease in term of circuit size for Power Amplifier (PA). The technology used relies on 0.25-µm GaAs Pseudomorphic High Electron Mobility Transistors (PHEMT) of United Monolithic Semiconductors (UMS) foundry. A distributed approach is proposed in order to model this power cell. The challenge consists to obtain, with a better shape factor (ratio between the vertical and horizontal sizes of the transistor), the same performances than a single transistor with the same gate development. In order to design a 2W amplifier, we have used two 12×100 µm transistors. Cascode vertical size is 413 µm whereas a transistor with the same gate development exhibits a vertical size of 790 µm. Therefore the shape factor is nearly one as compared to a shape factor of 4 for a classical parallel architecture. This new device allows to decrease the MMIC amplifier area of 40 % compared with amplifier based on single transistors

Design, modeling and characterization of MMIC integrated cascode cell for compact Ku-band power amplifiers

International audienceThis paper reports on the design of a new power cell dedicated to Ku-band power amplifier (PA) applications. This cell called "integrated cascode" has been designed in order to propose a strong decrease in terms of circuit size for PA. The technology used relies on 0.25-μm GaAs pseudomorphic high electron mobility transistors (PHEMT) of United Monolithic Semiconductors (UMS) foundry. A distributed approach is proposed in order to model this power cell. The challenge consists of obtaining, with a better shape factor (ratio between the vertical and horizontal sizes of the transistor), the same performances than a single transistor with the same gate width. In order to design a 2W amplifier, we have used two 12 × 100 μm transistors. Cascode vertical size is 413 μm whereas a transistor with the same gate width exhibits a vertical size of 790 μm. Therefore, the shape factor is nearly one as compared to a shape factor of 4 for a classical parallel architecture. This new device allows us to decrease the Monolithic microwave integrated circuit amplifier area of 40% compared to amplifier based on single transistors

Nouvelles cellules de puissance compactes pour des applications bande Ku en technologie MMIC

National audienceUne conception dune nouvelle cellule de puissance à base de transistor PHEMT AsGa de longueur de grille 0.25 μm en technologie MMIC est présentée dans ce papier. Le point de départ est la cellule de puissance fishbone développée initialement par UMS. Cette dernière va nous permettre de valider un modèle de transistor de petite taille qui sera utilisé pour la conception dautres cellules de puissances telles que la cellule cascode

Expanded polytetrafluoroethylene graft for bypass surgery using the excimer laser-assisted nonocclusive anastomosis technique

OBJECT: Patients with complex craniocerebral pathophysiologies such as giant cerebral aneurysms, skull base tumors, and/or carotid artery occlusive disease are candidates for a revascularization procedure to augment or preserve cerebral blood flow. However, the brain is susceptible to ischemia, and therefore the excimer laser-assisted nonocclusive anastomosis (ELANA) technique has been developed to overcome temporary occlusion. Harvesting autologous vessels of reasonable quality, which is necessary for this technique, may at times be problematic or impossible due to the underlying systemic vascular disease. The use of artificial vessels is therefore an alternative graft for revascularization. Note, however, that it is unknown to what degree these grafts are subject to occlusion using the ELANA anastomosis technique. Therefore, the authors studied the ELANA technique in combination with an expanded polytetrafluoroethylene (ePTFE) graft. METHODS: The experimental surgeries involved bypassing the abdominal aorta in the rabbit. Ten rabbits were subjected to operations representing 20 ePTFE graft-ELANA end-to-side anastomoses. Intraoperative blood flow, followup angiograms, and long-term histological characteristics were assessed 75, 125, and 180 days postoperatively. Angiography results proved long-term patency of ePTFE grafts in all animals at all time points studied. Data from the histological analysis showed minimal intimal reaction at the anastomosis site up to 180 days postoperatively. Endothelialization of the ePTFE graft was progressive over time. CONCLUSIONS: The ELANA technique in combination with the ePTFE graft seems to have favorable attributes for end-to-side anastomoses and may be suitable for bypass procedures