The recipient splenic artery for arterialization in orthotopic liver transplantation

Adequate hepatic arterial reconstruction is essential for successful liver transplantation. In the case of insufficient recipient hepatic arterial flow, most surgeons recommend the use of the aorta for arterialization of the graft. We report here on a technique in which the recipient splenic artery is used in such a setting. The splenic artery is dissected from its origin on a 3-to-4 cm segment and divided. The proximal segment is flipped to the right and anastomosed to the graft's celiac axis in an end-to-end fashion. This technique was used in 7 of 79 orthotopic liver transplantations (9%) because the native hepatic artery was deemed to be inadequate for anastomosis. There were no complications related to the use of this technique and no arterial thromboses. Arterialization of hepatic grafts using the recipient proximal splenic artery is a simple, safe, and efficient technique that can be recommended in the presence of an inadequate recipient hepatic arterial flow.     

Stress intensity factors for several groups of equal and parallel cracks in finite plates

Several groups of equal and parallel 2D cracks in finite width plates subjected to remote tensile loading have been studied. Formulae for calculating the stress intensity factors of these crack configurations have been proposed from the finite element analysis, and the difference between the formulae and the finite element results is smaller than 3%. On this basis, the influence of crack interactions on stress intensity factors (SIF) is discussed, and it can be seen that interaction between multiple cracks could produce either strong enhancement or shielding effects on the SIF depending on the crack positions and lengths.     

Platinum supported on resorcinol–formaldehyde based carbon aerogels for PEMFC electrodes: Influence of the carbon support on electrocatalytic properties

Two carbon aerogels with different nanopore size distributions but both with high surface area, high nanoporous volume and low bulk density have been compared as platinum support. The influence of the nanostructure of the carbon aerogel on the platinum nanoparticle deposit was investigated. The platinum was deposited on the carbon by means of two different techniques, one employing an anionic platinum precursor, the other using a cationic one. The porosity of the carbon aerogels was characterized by combining N₂-sorption and mercury porosimetry. The platinum deposit was characterized by transmission electron microscopy and rotating disk electrode experimentation to measure the platinum active surface area and its activity towards oxygen reduction reaction (ORR). The structural differences between the carbon aerogels did not yield any difference in platinum deposits in terms of Pt-surface area and ORR activity. Interestingly, the ORR mass activity of the high Pt-surface area samples, obtained by the cationic insertion technique, was several times lower than that of the samples obtained by the anionic technique. This observation was attributed to the particle size effect, detrimental in the case of platinum particle size around 1 nm.     

Use of laser energy to treat central pulmonary emboli: a preliminary report

We evaluated the ability and safety of a laser fiber placed percutaneously into a pig's lobar pulmonary artery to lyse pulmonary artery blood clots that were created in situ. We developed a model to create blood clots in situ that could be placed in any desired location with a radio-opaque marker at the clot position. An excimer laser delivered energy to a flexible 600 microns fiber in three experiments and a coaxial 1.6 mm multifiber catheter in the last experiment. Pre- and postprocedure angiograms obtained from each experiment demonstrated that partial laser dissolution of central pulmonary emboli in four pigs was accomplished successfully. To avoid perforation, it is imperative that the laser fiber remain coaxial during the entire lasing process. These results suggest that laser dissolution may become an adjunctive procedure for the treatment of central pulmonary emboli in those patients who cannot be treated medically.     

Reporting Red—Blue Intersections between Two Sets of Connected Line Segments

Abstract. We present a new line sweep algorithm, HEAPSWEEP, for reporting bichromatic (``purple') intersections between a red and a blue family of line segments. If the union of the segments in each family is connected as a point set, HEAPSWEEP reports all k purple intersections in time O((n+k) α(n) log ³ n) , where n is the total number of input segments and α(n) is the nearly constant inverse Ackermann function. To achieve these bounds, the algorithm maintains only partial information about the vertical ordering between curves of the same color, using a new data structure called a kinetic queue . In order to analyze the running time of HEAPSWEEP, we also show that a simple polygon containing a set of n line segments can be partitioned into monotone regions by a set of vertical threads cutting these segments O(n log n) times.     

Bacterial epidemiology of chronic otitis. Prophylactic and therapeutic deductions

The early onset sensory motor hereditary neuropathy (HSMN) can be divided into two forms: the early onset type (HSMN type III or Dejerine-Sottas) and the congenital hypomyelinating neuropathy (CHN). In both cases, abnormalities of myelination are present in peripheral nerves. Symptoms include hypotonia, weakness, hypotrophy, and areflexia. Skeletal changes may be present. In CHN symptoms may be present at birth and are rapidly progressive. Many authors actually consider the two forms different. The diagnosis is based only on clinical and neuropathological criteria. Here we report a case with a typical phenotype of HSMN type III but with peripheral nerve bioptic findings suggesting a CHN.     

Purification and characterization of an alkaline elastase from Myxococcus xanthus

An extracellular elastase, termed Myxococcus xanthus alkaline protease 1 (MAP1), has been purified from M. xanthus DK1622 culture supernatants by a combination of ion-exchange and affinity chromatographies. It consists of a single peptide chain of 39 kDa. The elastolytic activity was totally suppressed by 10 mM 1,10-phenanthroline and the enzyme may then be classified as a metalloprotease. Its pH optimum was estimated to be 8.2 with both elastin-orcein and succinyl-Ala3 p-nitroanilide as substrates. Despite its low pI (5.2), MAP1 was adsorbed on elastin at 80%, a result which privileges hydrophobic interactions between MAP1 and elastin rather than salt bridges, as for known basic elastases. About 80% of the original amidasic and elastolytic activities were conserved after a 30-min prior incubation of the enzyme at 40 degrees C; however, 70% of the amidasic activity is measured, instead of 15% for the elastolytic activity, after 30 min at 50 degrees C. Thermal denaturation at this temperature may prevent adsorption of the enzyme on elastin without any important change of the elastase structure. MAP1 readily hydrolyzes the Gly23-Phe24 bond in the oxidized insulin B chain; the peptide bonds Ala14-Leu15, Leu15-Tyr16, Phe24-Phe25, Phe25-Tyr26 are also cleaved, suggesting a primary specificity of the enzyme for hydrophobic or aromatic residues at the first amino acid towards the C-terminus from the cleavage site (P'1 position) [Schechter, I. & Berger, A. (1967) Biochem. Biophys. Res. Commun. 27, 157-162]. This hypothesis is consistent with the fact that Ala2-Phe-Ala and Ala3-Phe-Ala are hydrolyzed even though tri-alanine to hexa-alanine oligomers are not. The evidence of an elastase with the same molecular mass and pI as MAP1 is given during fruiting body development in submerged culture of M. xanthus. The fact that aromatic amino acids have been found to be the most representative of A-signal [Kuspa, A., Plamann, L. & Kaiser, D. (1992) J. Bacteriol. 174, 3319-3326] is consistent with the hypothesis that, regarding its specificity, MAP1 is likely to play a role in development of myxobacteria.     

RECP: A Reactor Designed to Test the Effect of a Catalyst on Soot Oxidation in a Diesel Particulate Filter

A new reactor designed to test soot combustion on a filter coated with an oxidation catalyst is described. It is designed to achieve screening investigations of catalysts in realistic conditions, i.e., close to those prevailing in a diesel particulate filter (DPF). In a DPF a soot layer is formed at the surface of a porous wall (filtration area) which may or may not be covered with a catalytic layer. In this new setup, the soot is deposited on a sample of a DPF which can be easily impregnated with oxidation catalysts. A model soot (commercial carbon black) is used for the investigation, and different procedures for the soot „deposit on the filter are tested.