A.c.-impedance spectroscopy study of oxygen reduction at Nafion® coated gas-diffusion electrodes in sulphuric acid: Teflon loading and methanol cross-over effects

The kinetics of oxygen reduction have been studied at Nafion®-coated dual layer gas-diffusion electrodes at 60 °C in 2.5 M H₂SO₄. A.c. impedance and steady state galvanostatic measurements have been carried out on electrodes containing various PTFE loadings. A.c. impedance spectroscopy supplied information on charge transfer resistance, series resistance and double layer capacitance of electrodes during the oxygen reduction process. These parameters, together with those derived by d.c. measurements (i.e. Tafel slopes, charge transfer coefficient, etc.), allowed a better identification of the features governing the electrode efficiency and the reduction mechanism. The best electrode was found to be one containing 30% PTFE; this showed both the lowest charge transfer resistance and the lowest overpotential for oxygen reduction. This electrode also showed lower overpotential than the same uncoated electrode at low current densities. The poisoning effect by methanol has been also investigated. Upon addition of methanol to the solution, no change was observed in the reaction mechanism at low overpotentials. In contrast, a significant variation of the Tafel slope was observed at high overpotentials. This behaviour is interpreted in terms of the variation of Pt-O bond strength as a function of electrode potential.     

Intensive child-centered play therapy with child witnesses of domestic violence.

Examined the effectiveness of child-centered play therapy sessions every day for 2 wks as an intervention for child witnesses of domestic violence. 22 children (aged 4–10 yrs) participated. The analyses of covariance indicated that children in the experimental group experience a significant increase in self-concept, a significant decrease in external and total behavior problems, a significant increase in the play behavior of physical proximity to the therapist, and a significant increase in the play behavior of nurturing and creative play themes. The results support utilizing intensive play therapy to treat child witnesses of domestic violence. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Steal phenomenon from mammary side branches: when does it occur?

BACKGROUND: The hemodynamic significance of patent mammary graft side branches is still controversial. This study was designed to evaluate the potential for flow steal of patent mammary side branches in different hemodynamic conditions. METHODS: Echo-Doppler measurement of mammary graft flow was performed at rest and after dipyridamole-induced coronary vasodilatation in 10 patients with angiographic demonstration of evident mammary graft side branches (study group) and in 10 matched control patients (control group). Concomitant thallium-201 myocardial scintigraphy was performed to assess the adequacy of mammary flow to the myocardial oxygen demand. Patients of the study group were also submitted to flow evaluation in condition of selective muscular or combined systemic and coronary relaxation. RESULTS: No difference in mammary flow and adequacy to myocardial oxygen demand was detected between patients of the study and control groups both at rest and after dipyridamole infusion. In patients with patent side branches the systolic-to-diastolic flow ratio was maintained in case of combined coronary and peripheral vasodilatation, whereas selective muscular relaxation led to an increase in the systolic and a reduction in the diastolic flow. CONCLUSIONS: Flow steal from patent mammary graft side branches is possible only in case of selective muscular vasodilatation. As this situation is unlikely to occur in the clinical setting, the potential for flow steal of mammary side branches in cardiac surgery patients seems to be minimal.     

Trypanothione overproduction and resistance to antimonials and arsenicals in Leishmania

Leishmania resistant to arsenicals and antimonials extrude arsenite. Previous results of arsenite uptake into plasma membrane-enriched vesicles suggested that the transported species is a thiol adduct of arsenite. In this paper, we demonstrate that promastigotes of arsenite-resistant Leishmania tarentolae have increased levels of intracellular thiols. High-pressure liquid chromatography of the total thiols showed that a single peak of material was elevated almost 40-fold. The major species in this peak was identified by matrix-assisted laser desorption/ionization mass spectrometry as N1,N8-bis-(glutathionyl)spermidine (trypanothione). The trypanothione adduct of arsenite was effectively transported by the As-thiol pump. No difference in pump activity was observed in wild type and mutants. A model for drug resistance is proposed in which Sb(V)/As(V)-containing compounds, including the antileishmanial drug Pentostam, are reduced intracellularly to Sb(III)/As(III), conjugated to trypanothione, and extruded by the As-thiol pump. The rate-limiting step in resistance is proposed to be formation of the metalloid-thiol pump substrates, so that increased synthesis of trypanothione produces resistance. Increased synthesis of the substrate rather than an increase in the number of pump molecules is a novel mechanism for drug resistance.     

Concept formation from design cases: why reusing experience and why not

This paper describes an environment that supports novice information systems designers in initial concept formation by organising design `cases' in evolving networks, automatically clustered by a neural agent to suggest generalisations of design patterns. Flexible reframing of the cases also supports creativity by uncovering less obvious but relevant design concepts. If the responsibility, of linking related design cases is distributed to a population of learners who contribute their cases and tentative generalisations, genetic techniques can be applied to sustain the evolution of the base of cases towards ontological forms that better guide and constrain the case reuse process, thus supporting knowledge transfer.     

A 25-week placebo-controlled study of eptastigmine in patients with Alzheimer disease

Studies of Pneumocystis carinii have been limited by our inability to propagate it in continuous culture. In this context, studies of P. carinii antigens have provided significant insight into the biology of this organism. The mannose-rich surface major surface glycoprotein of P. carinii termed glycoprotein A (gpA) is the best studied of these P. carinii antigens. Significant genetic and immunologic diversity exists between the gpA molecules expressed by P. carinii derived from different mammalian sources. The molecular and biochemical nature of gpA and other P. carinii antigens including p55 are reviewed. In addition, available information concerning the role of P. carinii gpA and other antigens in host-organism interactions are also discussed.     

Laparoscopic +proctopexy

BACKGROUND: Although not common, rectal prolapse in adults can often be a debilitating conditions. Its only effective treatment is surgical. Among the many procedures described for the treatment of rectal prolapse, abdominal rectopexy is one of the preferred. It consists of fixation of the rectum to the sacrum and does not require any intestinal resection or anastomosis. However, like all open abdominal surgery associated with a large incision this operation may result in significant morbidity which is exacerbated by the advanced age of the patient. METHODS: An abdominal rectopexy carried out completely laparoscopically is described. The rectum is fully mobilised down to the pelvic floor and then fixed to the sacrum employing a polypropylene mesh. The mesh is first stapled to the sacral hollow and then sutured on both sides of the rectum. Thus the mesh is wrapped around the lateral aspects of the rectum, but the anterior rectal wall is left free. Laparoscopic techniques have been applied to a wide range of benign and malignant colorectal procedures. RESULTS: However most of colorectal laparoscopic techniques involving bowel resection, are technically demanding and require often an abdominal incision to deliver the specimen and fashion the anastomosis. CONCLUSIONS: Without the need for bowel resection, the laparoscopic rectopexy may constitute an optimal application of laparoscopic colorectal techniques and may soon become the gold standard for the treatment of rectal prolapse.