Dependence of endothelial cell growth on substrate-bound fibronectin

A better understanding of the mechanism of adhesion, spreading and proliferation of human endothelial cells (HEC) on polymeric surfaces may lead to the development of vascular prostheses which allow the formation of an endothelial lining on the luminal surface. In the present investigation the interaction of HEC with polyethylene precoated with monoclonal antibodies directed against HEC membrane antigens and against extracellular matrix compounds was studied. F(ab¿)2 fragments of a monoclonal antibody, directed against an endothelial cell membrane antigen, and F(ab')2 fragments of a monoclonal antibody, directed against cellular fibronectin, were also included in this study. Preadsorption of these antibodies and F(ab')2 fragments, including mixtures of antibodies and mixtures of F(ab')2 fragments, resulted in cell adhesion and spreading as well as moderate cell proliferation (or no proliferation) for several days. However, a good proliferation of HEC was only observed on polyethylene precoated with fibronectin or CLB-HEC-FN-140 (directed against fibronectin). These results strongly suggest that fibronectin, bound to a solid substrate, provides a biochemical signal necessary for the proliferation of HEC. The initial proliferation of HEC on other preadsorbed antibodies or F(ab')2 fragments may be explained by the fact that suspended HEC, used for cell seeding, still possess cell membrane-bound fibronectin

The role of cellular fibronectin in the interaction of human endothelial cells with polymers

During in-vitro adhesion, spreading and proliferation of human endothelial cells (HEC) on tissue culture polystyrene (TCPS), cellular fibronectin is deposited onto the surface of TCPS in spite of the fact that relatively large amounts of proteins have been adsorbed from the serum-containing culture medium to this surface. Evidence is presented that serum proteins, adsorbed to the TCPS surface, are displaced by cellular fibronectin. In addition, the interaction of HEC with polyethylene, precoated with monoclonal antibodies directed against HEC membrane antigens and against extracellular matrix compounds, was studied. F(ab')2 fragments of two monoclonal antibodies were also included in this study. Preadsorption of these antibodies and F(ab')2 fragments resulted in cell adhesion and spreading as well as moderate cell proliferation (or no proliferation) for several days. A good cell proliferation of HEC was only observed on polyethylene precoated with fibronectin or an antibody directed against fibronectin. The results indicate that the direct or indirect deposition of fibronectin is a prerequisite for the proliferation of HEC. It is suggested that fibronectin, bound to a solid substrate, provides a biochemical signal necessary for the proliferation of HEC

The low-energy forms of photosystem I light-harvesting complexes: Spectroscopic properties and pigment-pigment interaction characteristics

In this work the spectroscopic properties of the special low-energy absorption bands of the outer antenna complexes of higher plant Photosystem I have been investigated by means of low-temperature absorption, fluorescence, and fluorescence line-narrowing experiments. It was found that the red-most absorption bands of Lhca3, Lhca4, and Lhca1-4 peak, respectively, at 704, 708, and 709 nm and are responsible for 725-, 733-, and 732-nm fluorescence emission bands. These bands are more red shifted compared to "normal" chlorophyll a (Chl a) bands present in light-harvesting complexes. The low-energy forms are characterized by a very large bandwidth (400-450 c

Acquisition of multidrug-resistant Enterobacterales during international travel: A systematic review of clinical and microbiological characteristics and meta-analyses of risk factors

Background: International tourism increased from 25 million tourist arrivals in 1950 to over 1.3 billion in 2017. These travelers can be exposed to (multi) resistant microorganisms, may become colonized, and bring them back home. This systematic review aims to identify the carriage rates of multidrug-resistant Enterobacterales (MDR-E) among returning travelers, to identify microbiological methods used, and to identify the leading risk factors for acquiring MDR-E during international travel. Methods: Articles related to our research question were identified through a literature search in multiple databases (until June 18, 2019)-Embase, Medline Ovid, Cochrane, Scopus, Cinahl, Web of Science, and Google Scholar. Results: Out of 3211 potentially relevant articles, we included 22 studies in the systematic review, and 12 studies in 7 random-effects meta-analyses. Highest carriage rates of MDR-E were observed after travel to Southern Asia (median 71%), followed by travel to Northern Africa (median 42%). Carbapenemase-producing Enterobacterales (CPE) were identified in 5 out of 22 studies, from a few patients. However, in only eight out of 22 studies (36.4%) the initial laboratory method targeted detection of the presence of CPE in the original samples. The risk factor with the highest pooled odds ratio (OR) for MDR-E was travel to Southern Asia (pooled OR = 14.16, 95% confidence interval [CI] = 5.50 to 36.45), followed by antibiotic use during travel (pooled OR = 2.78, 95% CI = 1.76 to 4.39). Conclusions: Risk of acquiring MDR-E while travelling increases depending on travel destination and if antibiotics are used during travel. This information is useful for the development of guidelines for healthcare facilities with low MDR-E prevalence rates to prevent admission of carriers without appropriate measures. The impact of such guidelines should be assessed