Low-artifact intravascular devices: MR imaging evaluation

Flow-phantom magnetic resonance (MR) imaging, with use of both spin-echo (SE) and gradient-echo (GRE) techniques at 1.5 T, was performed on the percutaneous Greenfield (beta-III titanium alloy [TMA wire]), Amplatz (MP32-N alloy), and Simon nitinol filters and TMA wire facsimiles of the bird's nest, Gunther, new retrievable, and Amplatz vena caval filters. SE imaging allowed detection of thrombi as small as 5 X 5 mm trapped within the percutaneous Greenfield, Simon nitinol, and TMA-wire facsimile filters; with the MP32-N Amplatz filter, a larger volume of thrombus (10 X 20-mm clots) was necessary for clot detection. GRE imaging allowed detection of intraluminal tilting of the percutaneous Greenfield and facsimile Amplatz (TMA-wire) filters. GRE imaging was useful for demonstrating postfilter turbulence due to clots, which was greatest for the Amplatz filter. Imaging of facsimile vascular devices made of tantalum or TMA wire did not cause the severe "black-hole" MR artifacts typical of the stainless-steel devices. SE and GRE imaging were very useful for determining caval patency in two patients with previously placed Mobin-Uddin filters. Noninvasive MR evaluation of blood vessels in the presence of a variety of low-artifact intravascular devices appears feasible.     

Activation of human peripheral blood mononuclear cells by nonpathogenic bacteria in vitro: evidence of NK cells as primary targets

The interaction of commensal bacteria with immunocompetent cells may occur in definite compartments of the mucosal immune system, as limited translocation through the epithelial barrier cannot be excluded. In this study the stimulation of human peripheral blood mononuclear cells and purified lymphocyte subsets by nonpathogenic gram-positive lactobacilli (Lactobacillus johnsonii and Lactobacillus sakei) and gram-negative Escherichia coli was investigated. The various bacterial strains induced a differential cytokine pattern. Whereas L. johnsonii and L. sakei strongly induced gamma interferon (IFN-gamma) and interleukin-12 (IL-12), E. coli and lipopolysaccharide (LPS) preferentially induced IL-10 after 16 h of stimulation. Expression of activation antigens CD69 and CD25 was observed on (CD3(-) CD56(+)) natural killer (NK) cells after stimulation of total human peripheral blood mononuclear cells. All bacteria mediated the proliferation of human peripheral blood mononuclear cells, and the strongest proliferative response was observed with L. johnsonii. Purified CD4(+), CD8(+), and CD19(+) lymphocyte subsets were not activated upon bacterial stimulation but showed normal response to a mitogenic stimulus. In contrast, purified NK cells upregulated the IL-2Ralpha chain (CD25) and underwent proliferation when stimulated by L. johnsonii. E. coli and LPS were less effective in inducing proliferation. Expression of CD25 or secretion of IFN-gamma from purified NK cells was significantly increased in the presence of bacterially primed macrophages, indicating that full activation required both bacterium- and cell contact-based signals derived from accessory cells.     

Activated T-Lymphocytes Express Occludin, a Component of Tight Junctions

T-lymphocytes routinely traffic from the lymphoid and vascular compartments to the tissues during immune surveillance and inflammatory responses. This egress occurs without compromising endothelial barrier, which is maintained by tight junctions (zonula occludens). We report that T-lymphocytes up-regulate the expression of occludin, a major component of the tight junction in response to stimulation with phorbol ester (PMA) + calcium ionophore, CD3 antibody or T-cell receptor (TCR) antibody. Only activated T-lymphocytes express occludin; this adhesion molecule is nearly absent in resting T-lymphocytes. By immunofluorescence, occludin is seen in lymphocyte aggregates, but does not appear to mediate aggregation since only 50% of the cells in these clusters express occludin. Occludin is expressed between 8 and 24 h following stimulation, and persists for at least 48 h. These data indicate that activated T cells produce occludin which may regulate lymphocyte adhesion and trafficking.     

Interferon independence of genetically controlled resistance to flaviviruses.

Flavivirus-resistant C3H/RV mice injected with sheep anti-interferon globulin and then infected with either West Nile or yellow fever virus survived and displayed no disease symptoms. Also, treatment of embryo fibroblast cultures prepared from C3H/RV or congenic susceptible C3H/HE mice with anti-interferon serum resulted in an increased yield of West Nile virus from both types of cultures, but the amount of infectious virus produced by resistant cultures remained 1 to 1.5 logs lower than that produced by susceptible cell cultures. These results indicate that the mode of expression of the flavivirus resistance gene differs significantly from that of the Mx gene conferring resistance to influenza virus-induced disease in A2G mice.     

Life-threatening complications of extracorporeal treatment in patients with severe eosinophilia

We report three patients with massive eosinophilia of different etiology who developed bronchoconstriction, hypotension, and shock shortly after dialysis or leukapheresis had been begun. In two cases, ethylene oxide-free materials had been used ruling out an allergic reaction related to this compound. Degranulation of eosinophils with release of eosinophil peroxidase may have caused the observed adverse reactions, as suggested by in vitro experiments with blood from the three patients. Our observations draw attention to the fact that extracorporeal therapies may initiate life-threatening complications in patients with severe eosinophilia.     

Chronic changes in male rats' hormone-sensitive systems after suprathreshold pulses of testosterone

Adult male rats were castrated and maintained on daily SC injections of a threshold amount (200 micrograms) of testosterone propionate (TP). To mimic naturally occurring pulses of suprathreshold testicular hormones in intact males, animals in the experimental groups also received either one (single TP) or five (multiple TP) injections of 800 micrograms TP over 12 days. The rats were examined on the following day (acute) or 15 days later (chronic) for changes in hormone-sensitive behavior, physiology, and morphology. The hypothesis tested was that the hormonal pulses function to provoke chronic changes in substrates underlying the reproductive system. The results were that multiple doses of suprathreshold TP provoked acute modifications in aggressive behavior, sex accessory glands, and glans penis integrity. Chronic changes were observed in sex accessory gland functioning and penile morphology, particularly in the size of penile papillae. A single exposure to suprathreshold TP was considerably less effective, though there was some evidence of acute changes in sex accessory glands and chronic changes in penile papillae. There was substantial variation in the responses of individual animals, particularly the chronic responses. The data were interpreted as supporting the hypothesis.     

Histone H1-mediated transfection: role of calcium in the cellular uptake and intracellular fate of H1-DNA complexes

Previously, we have shown that the transgene expression in the endothelial cell line ECV 304 strongly depends on the presence of low concentrations of Ca2+. However, it remained unclear, which transfection steps are controlled by Ca2+ ions. In the present study, we constructed transfection complexes of digoxigenin-labelled DNA and FITC-labelled histone H1. We monitored the pathway of these complexes with the use of anti-digoxigenin and anti-cathepsin B antibodies and immunofluorescence microscopy. Double labelling of DNA and cathepsin B permitted the localization of transfection complexes into endosomes/lysosomes which suggests an uptake of transfection complexes via endocytosis. It was also found that the uptake of transfection complexes by the cells was independent of the presence or absence of Ca2+ ions in the transfection medium. On the other hand, the presence of Ca2+ in the transfection medium dramatically changed the composition of the transfection complexes inside the endosome/lysosome compartment, which resulted in a strong reduction of H1 binding to DNA. Presence of Ca2+ in the postincubation medium for 24 h resulted in release of the transfection complexes with reduced H1 content from the endosomes/lysosomes into the cytosol. In the absence of Ca2+ the transfection complexes practically disappeared. These results allow us to come to the following conclusions: Ca2+ ions control the reorganization of the transfection complexes in endosomes/lysosomes and their release into the cytosol, which is an important prerequisite for transgene expression, whereas uptake of transfection complexes by the cells is not dependent on Ca2+.     

Poliovirus translation initiation: differential effects of directed and selected mutations in the 5' noncoding region of viral RNAs.

We have analyzed the translational defects of a number of mutations in the 5' noncoding region of poliovirus type 1 RNA. These mutations fall into three categories: (1) two mutations which resulted in temperature sensitive (ts) viruses, (2) the second-site mutations responsible for the reversion of the two ts viruses, and (3) mutations which were lethal to virus production. RNAs containing either of the ts mutations translated in vitro at levels significantly lower than wild-type levels. RNAs containing the respective second-site reversions had corrected these translational defects to levels corresponding to their viral growth potentials. Unlike in vitro translation of wild-type poliovirus RNA, translation of the RNAs which gave rise to ts mutant viruses was not stimulated by the addition of an S10 fraction from an uninfected HeLa cell extract to a rabbit reticulocyte lysate (RRL). In vitro translation of the mutant RNAs (corresponding to the ts viruses) in a RRL was stimulated by factors present in a ribosomal salt wash (RSW) from a HeLa extract, although the levels of stimulation were only half those seen for wild-type. These results suggest that the stimulatory factors present in the RSW have a decreased affinity for the mutant RNA templates but can, to some extent interact, with such RNAs if provided in high enough concentration. The in vitro translation of RNAs containing either of the lethal mutations was not stimulated by factors present in the S10 or the RSW. Taken together, our data suggest a correlation between the ability of a genetically altered RNA to respond to translation stimulatory factors in vitro and the ability of that mutation to be recovered in infectious virus. In addition, we have identified the in vivo-selected reversion of translational defects for two different ts viruses.