18 research outputs found

    Collateral circulation: Past and present

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    Following an arterial occlusion outward remodeling of pre-existent inter-connecting arterioles occurs by proliferation of vascular smooth muscle and endothelial cells. This is initiated by deformation of the endothelial cells through increased pulsatile fluid shear stress (FSS) caused by the steep pressure gradient between the high pre-occlusive and the very low post-occlusive pressure regions that are interconnected by collateral vessels. Shear stress leads to the activation and expression of all NOS isoforms and NO production, followed by endothelial VEGF secretion, which induces MCP-1 synthesis in endothelium and in the smooth muscle of the media. This leads to attraction and activation of monocytes and T-cells into the adventitial space (peripheral collateral vessels) or attachment of these cells to the endothelium (coronary collaterals). Mononuclear cells produce proteases and growth factors to digest the extra-cellular scaffold and allow motility and provide space for the new cells. They also produce NO from iNOS, which is essential for arteriogenesis. The bulk of new tissue production is carried by the smooth muscles of the media, which transform their phenotype from a contractile into a synthetic and proliferative one. Important roles are played by actin binding proteins like ABRA, cofilin, and thymosin beta 4 which determine actin polymerization and maturation. Integrins and connexins are markedly up-regulated. A key role in this concerted action which leads to a 2-to-20 fold increase in vascular diameter, depending on species size (mouse versus human) are the transcription factors AP-1, egr-1, carp, ets, by the Rho pathway and by the Mitogen Activated Kinases ERK-1 and -2. In spite of the enormous increase in tissue mass (up to 50-fold) the degree of functional restoration of blood flow capacity is incomplete and ends at 30% of maximal conductance (coronary) and 40% in the vascular periphery. The process of arteriogenesis can be drastically stimulated by increases in FSS (arterio-venous fistulas) and can be completely blocked by inhibition of NO production, by pharmacological blockade of VEGF-A and by the inhibition of the Rho-pathway. Pharmacological stimulation of arteriogenesis, important for the treatment of arterial occlusive diseases, seems feasible with NO donors

    Comparative in vitro activity of oral antimicrobial agents against Enterobacteriaceae from patients with community-acquired urinary tract infections in three European countries

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    Enterobacteriaceae causing community-acquired urinary tract infections were examined in selected outpatient clinics and hospitals in Belgium, Germany and Spain using EUCAST breakpoints for susceptibility. A total of 1190 isolates were collected. Escherichia coli isolates were resistant to amoxicillin-clavulanic acid (28.1%), ciprofloxacin (23.4%) and trimethoprim-sulfamethoxazole (21.4%) compared with fosfomycin and nitrofurantoin (each, < 1.5%). Ceftibuten (MIC50/90 0.25/0.5 mg/L) and ceftriaxone activity (MIC50/90 <= 0.25 mg/L) was comparable. Ceftibuten (MIC90 <= 0.25 mg/L) was also active against Proteus mirabilis and Klebsiella spp. Extended-spectrum beta-lactamase phenotypes were 7.1% for E. coli, 5.6% for Klebsiella pneumoniae and 0.4% for P. mirabilis. Resistance was common among men and elderly women. (C) 2015 European Society of Clinical Microbiology and Infectious Diseases. Published by Elsevier Ltd. All rights reserved

    Evaluation of an infectious disease consultation programme in a German tertiary care hospital

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    To evaluate a newly implemented infectious disease (ID) consultation service in terms of patient care, outcome and antibiotic prescription and to describe factors influencing adherence to recommendations. Data from consultations during the first 6 months of the ID consultation program were collected and evaluated. Consultation requests, diagnostic results, treatment outcomes and antibiotic recommendations were categorised. Diagnostic and therapeutic recommendations were assessed and rated for adherence and outcome. Statistical analysis was performed to identify factors influencing adherence and treatment outcome. A total of 251 consultations were assessed. In most cases, ID specialists were asked for further advice regarding a previously initiated anti-infective treatment (N = 131, 52 %). In 54 of 195 (28 %) first consultations, the ID specialist proposed a differential diagnosis that differed from that of the working diagnoses submitted with the consultation request, and which was subsequently confirmed in 80 % of these cases. Diagnostic and therapeutic recommendations were made in 190 (76 %) and 240 (96 %) of the consultations, respectively. A change in the current treatment was recommended in 66 % of consultations; 37 % of recommendations were cost-saving and 26 % were cost-neutral. Compliance with diagnostic and therapeutic recommendations was rated as good by pre-specified criteria in 65 and 86 % of consultations, respectively. Treatment outcome was correlated with adherence to diagnostic recommendations (P = 0.012). Twenty-nine patients (16 %) died during the same hospital stay. Infectious disease consultations may help to establish the correct diagnosis, resulting in the appropriate treatment being provided to a severely sick patient population. Treatment outcome was improved in cases of good diagnostic adherence to the recommendations of the ID specialist

    Modulation of surgical fibrosis by microbial zwitterionic polysaccharides

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    Bacterial carbohydrates have long been considered T cell-independent antigens that primarily induce humoral immune responses. Recently, it has been demonstrated that bacterial capsules that possess a zwitterionic charge motif can activate CD4(+) T cells after processing and presentation by antigen-presenting cells. Here we show that these zwitterionic polysaccharides can prevent T helper 1-mediated fibrosis by signaling for the release of IL-10 from CD4(+) T cells in vivo. IL-10 production by these T cells and their ability to prevent fibrosis is controlled by the inducible costimulator (ICOS)-ICOS ligand pathway. These data demonstrate that the interaction of the zwitterionic polysaccharides with T cells results in modulation of surgical fibrosis in vivo and suggest a previously undescribed approach to “harnessing” T cell function to prevent inflammatory tissue disorders in humans

    Immunochemical and Biological Characterization of Three Capsular Polysaccharides from a Single Bacteroides fragilis Strain

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    Although Bacteroides fragilis accounts for only 0.5% of the normal human colonic flora, it is the anaerobic species most frequently isolated from intra-abdominal and other infections with an intestinal source. The capsular polysaccharides of B. fragilis are part of a complex of surface polysaccharides and are the organism's most important virulence factors in the formation of intra-abdominal abscesses. Two capsular polysaccharides from strain NCTC 9343, PS A1 and PS B1, have been characterized structurally. Their most striking feature is a zwitterionic charge motif consisting of both positively and negatively charged substituent groups on each repeating unit. This zwitterionic motif is essential for abscess formation. In this study, we sought to elucidate structural features of the capsular polysaccharide complex of a commonly studied B. fragilis strain, 638R, that is distinct from strain 9343. We sought a more general picture of the species to establish basic structure-activity and structure-biosynthesis relationships among abscess-inducing polysaccharides. Strain 638R was found to have a capsular polysaccharide complex from which three distinct carbohydrates could be isolated by a complex purification procedure. Compositional and immunochemical studies demonstrated a zwitterionic charge motif common to all of the capsular polysaccharides that correlated with their ability to induce experimental intra-abdominal abscesses. Of interest is the range of net charges of the isolated polysaccharides—from positive (PS C2) to balanced (PS A2) to negative (PS 3). Relationships among structural components of the zwitterionic polysaccharides and their molecular biosynthesis loci were identified
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