Assessment of Atrial Electromechanical Delay Using Tissue Doppler Echocardiography in Children with Asthma

Right ventricular (RV) dysfunction, pulmonary hypertension, atrial enlargement, and cor pulmonale may be associated with asthma. These pathological conditions may disturb the electrophysiological properties of the right atrium. This study investigated the atrial electromechanical delay and P-wave dispersion (PWD) in patients with asthma. Thirty-four children aged 8–16 years who were being followed up for asthma constituted the patient group, and 34 age- and body mass index-matched patients constituted the control group. Both groups underwent RV tissue Doppler measurements, intra-right atrial conduction time (IRCT-echo) determination, intra-left atrial conduction time (ILCT-echo) determination, inter-atrial conduction time (IACT-echo) determination, and PWD measurement. The IRCT-echo (14.38 ± 5.46 and 8.20 ± 3.90 ms; p < 0.001) and IACT-echo (28.97 ± 6.58 and 22.79 ± 6.28 ms; p < 0.001) were higher in patients with asthma than in the control group. The PWD (44.58 ± 17.51 and 38.11 ± 13.50 ms; p = 0.09), maximum P-wave duration (87.94 ± 18.20 and 82.44 ± 16.36 ms, p = 0.19), minimum P-wave duration (43.58 ± 9.95 and 44.79 ± 9.13 ms; p = 0.60), and ILCT-echo (15.88 ± 5.40 and 14.58 ± 4.94 ms; p = 0.30) were similar between the two groups. The IRCT-echo was positively correlated with the isovolumetric relaxation time of the lateral tricuspid annulus (r = 0.60; p < 0.001) and with the myocardial performance index of the lateral tricuspid annulus (r = 0.59; p < 0.001) in patients with asthma. The IRCT-echo and IACT-echo were higher in patients with asthma than in the control group. The deterioration of the electrophysiological properties of the right atrium may result in a risk of atrial fibrillation in patients with asthma.     

Selective Interaction of a Cationic Polyfluorene with Model Lipid Membranes: Anionic versus Zwitterionic Lipids

This paper explores the interaction mechanism between the conjugated polyelectrolyte {[9,9-bis(6’-N,N,N-trimethylammonium)hexyl]fluorene-phenylene}bromide (HTMA-PFP) and model lipid membranes. The study was carried out using different biophysical techniques, mainly fluorescence spectroscopy and microscopy. Results show that despite the preferential interaction of HTMA-PFP with anionic lipids, HTMA-PFP shows affinity for zwitterionic lipids; although the interaction mechanism is different as well as HTMA-PFP’s final membrane location. Whilst the polyelectrolyte is embedded within the lipid bilayer in the anionic membrane, it remains close to the surface, forming aggregates that are sensitive to the physical state of the lipid bilayer in the zwitterionic system. The different interaction mechanism is reflected in the polyelectrolyte fluorescence spectrum, since the maximum shifts to longer wavelengths in the zwitterionic system. The intrinsic fluorescence of HTMA-PFP was used to visualize the interaction between polymer and vesicles via fluorescence microscopy, thanks to its high quantum yield and photostability. This technique allows the selectivity of the polyelectrolyte and higher affinity for anionic membranes to be observed. The results confirmed the appropriateness of using HTMA-PFP as a membrane fluorescent marker and suggest that, given its different behaviour towards anionic and zwitterionic membranes, HTMA-PFP could be used for selective recognition and imaging of bacteria over mammalian cells.     

Targeting of an activated T-cell subset using a bispecific antibody- toxin conjugate directed against CD4 and CD26

We have developed a bispecific antibody that recognizes the CD4 and CD26 antigens simultaneously and that was examined for its ability to target CD4+CD26+T cells. These latter cells constitute the activated component of the CD4+ CD29highCD45RO+ memory T-cell subset that provides help for B-cell Ig synthesis and help for responses against recall antigens. The purified bispecific antibody exhibited an estimated dissociation constant (kd) of 2.4 x 10(-9) mol/L, on comparison with 1.1 x 10(-9) mol/L for anti-CD26, and 1.6 x 10(-10) mol/L for anti-CD4. Surface plasmon resonance was used to show the bifunctional capacity of the antibody. On binding 125I-bispecific antibody to phytohemagglutinin (PHA)-activated T cells, 54.4% of the bound antibody was internalized. This was the result of bispecific binding, because monovalent fragments of anti-CD4 and anti-CD26 were not able to modulate antigen or induce internalization using both a fluorescent assay and an 125I-internalization assay. The ability of the bispecific antibody to be internalized was used to deliver a toxin, blocked ricin, specifically to cells that are CD4+CD26+. The inability of monovalent fragments to be internalized formed the basis for our hypothesis that monovalent binding by the bispecific immunotoxin would not result in internalization. Against resting E+ T cells, the bispecific immunotoxin developed a minimal effect. On preactivating the same cells, using phorbol myristate acetate (PMA)/ionomycin on concanavalin A (ConA) or especially PHA, levels of CD26 were upregulated and the immunotoxin effectively inhibited the ability to provide help for B-cell Ig synthesis while leaving intact the CD4-CD26+ and CD4+CD26- populations; an effect observed both functionally and by phenotype. The bispecific antibody proved to be most effective at inhibiting a heterologous mixed leukocyte reaction. We propose that this reagent may form the basis for the rational design of toxins designed to modulate activated T cells from, or directed against, tissue grafts.     

Contribution of interleukin-1 to activation of coagulation and fibrinolysis, neutrophil degranulation, and the release of secretory- type phospholipase A2 in sepsis: studies in nonhuman primates after interleukin-1 alpha administration and during lethal bacteremia

Although studies with interleukin-1 receptor antagonist (IL-1ra) in animal models have shown that IL-1 contributes to mortality in sepsis, the mechanisms whereby IL-1 mediates lethal effects are not well established. A possible mechanism is that IL-1 enhances the activation and release of other inflammatory mediator systems such as coagulation, fibrinolysis, neutrophils, and secretory-type phospholipase A2 (sPLA2). We investigated this possibility by assessing the effect of intravenously injected recombinant human IL-1 alpha (rhIL-1 alpha) on these plasma parameters in baboons. In addition, we examined the course of these inflammatory parameters in baboons after a challenge with a lethal dose of Escherichia coli and while receiving a 24-hour constant infusion of IL-1ra or placebo. Intravenous administration of IL-1 alpha (10 micrograms/kg) induced the formation of thrombin, as evidenced by the appearance of thrombin-antithrombin III (TAT) complexes into the circulation (peak levels, 188 +/- 92 ng/mL at 2 hours), as well as the activation of fibrinolysis, assessed by circulating plasmin-alpha 2- antiplasmin complexes (PAP complexes; peak levels, 0.4% +/- 0.03% of fully activated plasma at 1 hour), the release of tissue-type plasminogen activator (t-PA; peak levels, 6 +/- 2 ng/mL at 2 hours), and its inhibitor, plasminogen activator inhibitor (PAI; peak levels, 724 +/- 246 ng/mL at 4 hours). Il-1 alpha administration also induced the release of sPLA2 (maximal levels, 336 +/- 185 ng/mL at 8 hours), but not degranulation of neutrophils. In the septic baboons, a significant reduction of the formation of thrombin (peak TAT levels decreased from 582 +/- 78 ng/mL to 219 +/- 106 ng/mL; P < .005), the release of t-PA (peak levels decreased from 37 +/- 11 ng/mL to 17 +/- 2 ng/mL; P < .001), and its inhibitor, PAI (peak levels decreased from 2,639 +/- 974 ng/mL to 1,110 +/- 153 ng/mL; P <.001), was observed in the group receiving IL-1ra compared to that receiving placebo. The release of neutrophilic elastase was also significantly attenuated in IL-1a-treated animals (peak levels, 1,024 +/- 393 and 655 +/- 104 ng/mL in control and treatment groups, respectively; P < .05). The difference between sPLA2 levels in both groups, although higher in the controls (maximal levels, 3,140 +/- 1,435 ng/mL in control v 2,217 +/- 1,375 ng/mL in IL-1ra-treated group), was not significant. Thus, IL-1 contributes to activation of various other mediator systems in severe sepsis in nonhuman primates. We propose that these effects may explain the lethal actions of IL-1 in this sepsis model and suggest a similar role for IL-1 in severe human sepsis.     

Analysis of antigenic determinants on human monocytes and macrophages

Mo1, 2, 3, and 4, and Plt-1 are a series of five distinct antigens detected on the surface of human peripheral blood monocytes by mouse monoclonal antibodies. Mo2 and 3 are restricted to the monocyte- macrophage series, while Mo1, as previously reported, is also expressed by human granulocytes and null cells. Mo3, as distinguished from Mo1 and Mo2, is weakly expressed by virgin peripheral blood monocytes but becomes well expressed if monocytes are cultured overnight at 37 degrees C. Mo4 is coexpressed by monocytes and platelets, while Plt-1 appears to be a platelet-specific antigen whose detection on monocytes reflects adherence of platelets to monocyte membranes. That Mo2-4 are true monocyte antigens is demonstrated by their resynthesis following protease treatment of monocytes (Mol expression is resistant to proteolytic digestion). During myeloid-monocyte differentiation, the Mo antigens are infrequently expressed by immature myeloid cells but are found at higher frequency on leukemic monocytic forms. Macrophages from cultured peripheral blood monocytes and HL-60 cells exposed to lymphokines or phorbol diester express Mo1-4, but noncirculating peritoneal macrophages lack Mo3. The Mo antigens are differentiation markers whose expression reflects membrane heterogeneity during myeloid- monocyte-macrophage maturation.     

Transduction of primitive human hematopoietic cells with recombinant adenovirus vectors

We have examined the ability of recombinant adenoviral vectors to transduce human hematopoietic cells. Our findings indicate that adenovirus readily infects a large proportion of CD34+ cells. Using adenovirus vectors that transduce either a lacZ or an alkaline phosphatase reporter gene, we observed up to 45% of total CD34+ cells infected. Upon more detailed analysis, we observed comparable levels of transduction for CD34+/CD38- cells and for CD34+ cells in G(zero) phase of the cell cycle. Importantly, exposure to adenovirus resulted in negligible levels of toxicity as assayed by propidium iodide staining and colony-forming ability. Using adenovirus vectors, we also describe a model system for regulated gene expression in early hematopoietic tissues. CD34+ cells were simultaneously infected with two viruses, one carrying a TetR/VP16 transactivator (tTA) and the second carrying a tTA- dependent lacZ reporter gene. Using this approach, beta-gal expression was only observed upon coinfection with the transactivator vector. In addition, as shown previously (Gossen and Bujard, Proc Natl Acad Sci USA 89:5547, 1992), tetracycline was able to inhibit tTA mediated induction, thereby providing an effective means to regulate expression of the reporter gene. We conclude that recombinant adenovirus is an effective vehicle for transiently expressing genes in primitive human hematopoietic cells.     

接受激素替代疗法的绝经后亚洲妇女的干眼症

目的:比较接受和不接受激素替代疗法的绝经后妇女干眼症的发生情况。方法:采用横断面研究方法比较对照组和接受激素替代疗法的绝经后妇女干眼症的发生。对所有的受试者行泪液分泌实验,泪膜破裂时间和玫瑰红孟加拉染色检查。结果:总共54例妇女被纳入研究,其中接受激素替代疗法(第2组)30例(55.6%),对照组24例(44.4%)没有进行任何激素治疗(第1组)。在第2组中,11例服用雌激素(2A组),其余19例同时服用雌激素和孕酮(2B组)。在第1组组中有29.2%发生了干眼症,第2组为70.0%(P=0.003),进一步分析发现2B组(84.2%)较2A组(45.5%)更多发生了干眼症(P=0.042)。结论:本研究发现在绝经后服用激素的妇女中干眼症比较常见,它否定了先前激素替代疗法具有防止干眼症发生的假设。