Αρχειοθήκη ιστολογίου

Τρίτη 18 Απριλίου 2017

Isolated implant metastasis in chest wall due to seeding of transpleurally placed PTBD catheter tract in a case of hilar cholangiocarcinoma

Percutaneous transhepatic biliary drainage (PTBD) catheter site metastasis in cases of cholangiocarcinoma is reported sporadically. But it is unusual to see left-sided tumour metastasising to the right PTBD catheter site. Metastasis, in general, has a poor prognosis, but recurrence along the catheter tract in the absence of other systemic diseases can be a different scenario altogether. To date, there is no consensus on the management of this form of metastasis. But carefully selected patients can benefit from aggressive surgical resection. We report a case of a young patient with isolated chest wall metastasis 1 year after resection of left-sided hilar cholangiocarcinoma. The metastasis was resected and, on pathological analysis, was confirmed to be due to implantation of malignant cells along the tract of the PTBD catheter placed via a transpleural route.



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Fibrin sheath-associated endovascular infection of the heart: the Trojan horse of indwelling central venous catheters

Chronic indwelling central venous catheters can result in formation of fibrin sheaths increasing risk of occlusion, thrombosis and infection. Endovascular infection of right-sided heart structures induced by such sheaths is very rare. A 48-year-old woman with end-stage renal disease initially treated for diabetic ketoacidosis developed persistent Staphylococcus epidermidis bacteraemia without an identifiable source. Although transthoracic echocardiography was unremarkable, transoesophageal echocardiography revealed a fibrin sheath and vegetations in superior vena cava–right atrium junction, which was the site of the tip of a central catheter that had been removed 2 months prior, consistent with fibrin sheath-associated endovascular infection. The bacteraemia cleared and clinical improvement was seen with prolonged intravenous vancomycin. In patients with unexplained bacteraemia and history of a central catheter, rare causes of endovascular infections of right-sided heart structures like fibrin sheaths should be considered. These can persist months after catheter removal. Transoesophageal echocardiogram should be used for earlier detection.



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Hunting for nuclear short-range correlations : the connection to electroinduced two-nucleon knockout reactions



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More topics from the tropics: additional thoughts to Mammides et al.

Most studies on tropical conservation questions are conducted by researchers of developed countries from the north. This geographic disconnection was recently criticised by Mammides et al. Here, we reflect on their findings and add further views from scientist's and journal editor's perspectives. We argue that journals are, a priori, most strongly interested in research questions and approaches that will likely increase their scientific impact and prestige. This is rarely compatible with publishing articles on questions with restricted global impact or based on single taxa. We question whether small changes in the editorial policy of international conservation journals will considerably improve the geographic diversity in key conservation publications. Rather, thematic scopes of the leading conservation journals should be modified, preferably in close collaboration with leading conservationists from the south. We are convinced that long-term investments in the tropics will create a stronger local scientific community, thus bolstering academic morale, and finally may lead to an increase in the submission and acceptance rate of articles written from scientists from these regions.

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Nonlinear optics in a-Si:H-on-insulator and InGaP-on-insulator waveguide circuits



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Development of passive and active integrated silicon nitride photonics



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Contrasting Patterns of Species Richness and Functional Diversity in Bird Communities of East African Cloud Forest Fragments

Rapid fragmentation and degradation of large undisturbed habitats constitute major threats to biodiversity. Several studies have shown that populations in small and highly isolated habitat patches are prone to strong environmental and demographic stochasticity and increased risk of extinction. Based on community assembly theory, we predict recent rapid forest fragmentation to cause a decline in species and functional guild richness of forest birds combined with a high species turnover among habitat patches, and well defined dominance structures, if competition is the major driver of community assembly. To test these predictions, we analysed species co-occurrence, nestedness, and competitive strength to infer effects of interspecific competition, habitat structure, and species' traits on the assembly of bird species communities from 12 cloud forest fragments in southern Kenya. Our results do not point to a single ecological driver of variation in species composition. Interspecific competition does not appear to be a major driver of species segregation in small forest patches, while its relative importance appears to be higher in larger ones, which may be indicative for a generic shift from competition-dominated to colonisation-driven community structure with decreasing fragment size. Functional trait diversity was independent of fragment size after controlling for species richness. As fragmentation effects vary among feeding guilds and habitat generalists, in particular, tend to decline in low quality forest patches, we plead for taking species ecology fully into account when predicting tropical community responses to habitat change.

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