Plasma membrane cholesterol is a key molecule in shear stress-dependent activation of extracellular signal-regulated kinase

Shear stress, the dragging force generated by fluid flow, differentially activates extracellular signal-regulated kinase (ERK) and c-Jun NH2-terminal kinase (JNK) in bovine aortic endothelial cells (BAEC) (Jo, H., Sipos, K., Go, Y. M., Law, R., Rong, J., and McDonald, J. M. (1997) J. Biol. Chem. 272, 1395-1401). Here, we examine whether cholesterol-enriched compartments in the plasma membrane are responsible for such differential regulation. Pretreatment of BAEC with a cholesterol-binding antibiotic, filipin, did not inhibit shear-dependent activation of JNK. In contrast, filipin and other membrane-permeable cholesterol-binding agents (digitonin and nystatin), but not the lipid-binding agent xylazine, inhibited shear-dependent activation of ERK. The effect of cholesterol-binding drugs did not appear to be due to membrane permeabilization, since treatment of BAEC with a detergent, Triton X-100 which also permeabilizes membranes, did not inhibit shear-dependent activation of ERK. Furthermore, shear-dependent activation of ERK, but not JNK, was inhibited by cyclodextrin, a membrane-impermeable cholesterol-binding agent, which removes cell-surface cholesterol. Moreover, the effects of cyclodextrin were prevented by adding cholesterol during the incubation. These results indicate that cholesterol or cholesterol-sensitive compartments in the plasma membrane play a selective and essential role in activation of ERK, but not JNK, by shear stress. Although exposure to shear stress (1 h) increased the number of caveolae by 3-fold, treatment with filipin had no effect in either control or shear-exposed cells suggesting that caveolae density per se is not a crucial determinant in shear-dependent ERK activation. In summary, the current study suggests that cholesterol-sensitive microdomains in the plasma membrane, such as caveolae-like domains, play a critical role in differential activation of ERK and JNK by shear stress.     

The effect of Pseudomonas aeruginosa infection on clinical parameters in steady-state bronchiectasis

STUDY OBJECTIVE: To investigate the effect of Pseudomonas aeruginosa infection on clinical parameters in Chinese patients with noncystic fibrosis and steady-state bronchiectasis. DESIGN: Prospective, cross-sectional clinicomicrobiological study with informed consent. SETTING: Consecutive outpatient recruitment from a specialist bronchiectasis respiratory clinic. PATIENTS: Outpatients (n = 100; 62 women; 55.1+/-16.7 years old; FEV1/FVC 1.4+/-0.7/2.1+/-0.9 L), who had stable respiratory symptoms for more than 3 weeks. MEASUREMENTS AND RESULTS: Respiratory pathogens isolated from the sputum were: Pseudomonas aeruginosa (33), Haemophilus influenzae (10), Moraxella catarrhalis (2), other Gram-negative bacilli (5), Streptococcus pneumoniae (6), Staphylococcus aureus (5), mycobacteria (3), and yeast (1). Clinical parameters in patients with positive isolation of P aeruginosa were compared with those without the organism in the sputum culture (non-P aeruginosa). In the P aeruginosa group, the FEV1/FVC ratio and sputum volume were lower (p < 0.005) and higher (p < 0.0001), respectively, than those of the non-P aeruginosa group. The FEV1/FVC ratio (< 60%) and sputum volume (grading > 5) were independently associated with a positive sputum isolation of P aeruginosa with odds ratios of 3.1 (confidence interval [CI] 1.2 to 8.4; p < 0.01) and 4.7 (CI 1.6 to 13.3; p < 0.001), respectively. CONCLUSIONS: P aeruginosa is the predominant respiratory pathogen isolated in the sputum of Chinese patients with steady-state bronchiectasis, and its isolation is associated with high sputum output (> or = 75th quartile) and moderately severe airflow obstruction (FEV1/FVC < 60%).     

Development of a toxin-binding agent as a treatment for tunicaminyluracil toxicity: protection against tunicamycin poisoning of sheep

OBJECTIVE: To assess the ability of certain derivatives of beta-cyclodextrin to treat sheep affected by tunicaminyluracil toxicity, using tunicamycin poisoning as a model system. DESIGN: Controlled treatment trial. ANIMALS: One hundred and sixty Merino wethers were used in the studies. PROCEDURE: Groups of sheep were experimentally poisoned with tunicamycin. Derivatives of beta-cyclodextrin, with or without magnesium sulphate and magnesium gluconate, were administered to treatment groups daily for 2 to 3 days. Treatment groups were compared with untreated groups in terms of survival. RESULTS: A significant increase in survival was observed following treatment of tunicamycin-affected sheep with hydroxypropyl-beta-cyclodextrin (HP beta-CD) and magnesium sulphate in solution (P < 0.05). In subsequent trials, formulation of the cyclodextrin in the form of a magnesium gluconate gel suspension demonstrated significant protection (P < 0.01) and was equally as effective as the cyclodextrin in solution, but required half the frequency of administration, even when the treatment was not commenced until 24 h after the final toxin dose. Beta-cyclodextrin-epichlorohydrin copolymer also improved the survival rate. After toxin administration, the sheep lost significantly less weight if treatment with HP beta-CD was commenced early (P < 0.001). CONCLUSION: Protection studies using these two beta-cyclodextrin derivatives suggest that they may be effective in increasing the survival of sheep poisoned by tunicamycin and warrant further testing in field outbreaks of annual ryegrass toxicity.     

Comparison of PCR and pp65 antigenemia assay with quantitative shell vial culture for detection of cytomegalovirus in blood leukocytes from solid-organ transplant recipients

This study compared PCR and an assay for cytomegalovirus (CMV) pp65 antigenemia (CMV-vue; INCSTAR Corp.) with a quantitative shell vial culture (QSVC) technique for the detection of CMV in serial blood specimens from 46 solid-organ transplant recipients. In a comparison based on 535 specimens tested by PCR and QSVC, CMV was detected by PCR in 41 and by QSVC in 37 of 43 recipients at risk of CMV infection. The mean number of days after transplantation of initial detection of CMV was 29.9 for PCR and 34.0 for QSVC (P = 0.01). The antigenemia assay was performed on 395 specimens, including 304 of those also tested by PCR. In these specimens, CMV was detected by the antigenemia assay, QSVC, and PCR in 30, 32, and 35 (respectively) of 38 patients at risk, with no statistically significant difference in the time to detection. Each of the assays detected CMV in similar proportions of patients with and without clinically significant CMV infection. PCR stayed positive longer after transplantation than the other assays but frequently returned to negative when more than 6 months had elapsed after transplantation. The antigenemia assay and PCR stayed positive longer after institution of antiviral therapy than QSVC. PCR can provide highly sensitive detection of CMV viremia, but a PCR assay for CMV is not yet available in kit form. The pp65 antigenemia assay and shell vial culture are quantifiable and comparable in sensitivity. Either is recommended for rapid detection of CMV in blood specimens from solid-organ transplant recipients.     

Dbp5p, a cytosolic RNA helicase, is required for poly(A)+ RNA export

The DBP5 gene encodes a putative RNA helicase of unknown function in the yeast Saccharomyces cerevisiae. It is shown here that Dbp5p is an ATP-dependent RNA helicase required for polyadenylated [poly(A)+] RNA export. Surprisingly, Dbp5p is present predominantly, if not exclusively, in the cytoplasm, and is highly enriched around the nuclear envelope. This observation raises the possibility that Dbp5p may play a role in unloading or remodeling messenger RNA particles (mRNPs) upon arrival in the cytoplasm and in coupling mRNP export and translation. The functions of Dbp5p are likely to be conserved, since its potential homologues can be found in a variety of eukaryotic cells.     

Nursing performance measures go public

Over 100 years ago, Florence Nightingale showed caregivers how to analyze mortality data to improve their clinical processes. The nurses of today are facing a new performance measurement challenge. Consumers of health care services want information that will help them compare quality among providers. This article describes the types of nursing performance measures most appropriate to include on these public-oriented report cards and several issues that influence report card design and dissemination.     

Alteration without change?: a commentary on the proposed policy reforms of the British National Health Service

Magnesium chloride (MgCl2) has been proposed for the treatment of seizures of different etiologies. The present study investigated the effect of MgCl2 on aldrin-induced seizures. Initially, 50 male rats received 60 mg aldrin/kg po and the effects were classified as muscular twitches, clonic convulsions or tonic-clonic convulsions. Another group of 40 rats dosed with 60 mg aldrin/kg po received 0, 4, 8, or 12 mg MgCl2/kg i.m. The percentage of tonic-clonic convulsant rats that resulted from MgCl2 treatment were 90% at 0 mg/kg, 50% at 4 mg/kg, 40% at 8 mg/kg and 20% at 12 mg MgCl2/kg. The percentage of survivors in the group receiving 12 mg MgCl2/kg was 80% while the control group had 20% survival. The clonic convulsions were not modified by MgCl2 treatment. Blood and brain concentrations of aldrin and dieldrin (metabolite of aldrin) did not differ among groups. The MgCl2 administration decreased the neuroexcitability induced by aldrin and increased survivability.     

Formation and surface properties of electron-emissive coatings IV. DTA,ETA and dilatometry studies on some alkaline–earth hydroxides

The decomposition under vacuum of the hydroxides of calcium, strontium and barium was investigated by differential thermal analysis (DTA), electrothermal analysis (ETA) and dilatometry. The results suggest that the rate of sintering of calcium oxide is initially governed by the formation of a pseudo-hydroxide lattice; rapid sintering occurs only after conversion of this to the true oxide. Compacts of the oxides of strontium and barium show a remarkable resistance to sintering at temperatures up to 1000°. It is proposed that the sintering may have been inhibited by the presence of trace amounts of calcium oxide and strontium oxide formed by decomposition of impurities present in the samples of strontium and barium hydroxides, respectively.     

Interpretation time of serial chest CT examinations with stacked-metaphor workstation versus film alternator

PURPOSE: Interpretation time of serial staging chest CT cases, which each contained current and previous examinations, with a simple prototype workstation called filmstack was experimentally compared with interpretation time with a film alternator. MATERIALS AND METHODS: The filmstack displayed a "stack" of sections for each examination; user controls allowed rapid selection of preset attenuation windows and both synchronized and unsynchronized scrolling. Eight radiologists were timed as they used the filmstack and the film alternator to interpret four ergonomically complex serial CT cases. RESULTS: All reports dictated on the basis of findings with filmstack and film were of acceptable clinical accuracy. The time to examine a case with filmstack was significantly faster than the time with film, including the time to load and unload the alternator (99% confidence [P = .01]). There was no statistically significant difference in interpretation time between filmstack and prehung film. CONCLUSION: Use of a low-cost stacked CT workstation with a single 1,024 x 1,024 monitor is an effective means of interpreting cases that require comparison of multiple CT examinations.