Transient electronic structure and melting of a charge density wave in TbTe3.

Obtaining insight into microscopic cooperative effects is a fascinating topic in condensed matter research because, through self-coordination and collectivity, they can lead to instabilities with macroscopic impacts like phase transitions. We used femtosecond time- and angle-resolved photoelectron spectroscopy (trARPES) to optically pump and probe TbTe3, an excellent model system with which to study these effects. We drove a transient charge density wave melting, excited collective vibrations in TbTe3, and observed them through their time-, frequency-, and momentum-dependent influence on the electronic structure. We were able to identify the role of the observed collective vibration in the transition and to document the transition in real time. The information that we demonstrate as being accessible with trARPES will greatly enhance the understanding of all materials exhibiting collective phenomena.

Mechanism of the far-infrared absorption of carbon-nanotube films.

The far-infrared conductivity of single-wall carbon-nanotube ensembles is dominated by a broad absorption peak around 4 THz whose origin is still debated. We observe an overall depletion of this peak when the nanotubes are excited by a short visible laser pulse. This finding excludes optical absorption due to a particle-plasmon resonance and instead shows that interband transitions in tubes with an energy gap of approximately 10 meV dominate the far-infrared conductivity. A simple model based on an ensemble of two-level systems naturally explains the weak temperature dependence of the far-infrared conductivity by the tube-to-tube variation of the chemical potential.

Spatial mode cleaning by femtosecond filamentation in air.

By studying the conical emission of a blue femtosecond laser filament in air, it is shown that self-improvement of the beams' spatial mode quality occurs for a self-guided laser pulse.

Acute alcohol-induced protection against infarction in rabbit hearts: differences from and similarities to ischemic preconditioning.

Recent studies reveal that brief ethanol exposure induces cardioprotection against simulated ischemia in cardiomyocytes by the activation of protein kinase C- epsilon. The present study tests the ability of ethanol to induce protection in rabbit hearts in which infarct size was the end-point and explores the signal transduction pathways involved. In isolated rabbit hearts, 50 m m ethanol infused for 5 min with 10 min of washout prior to 30 min of regional ischemia reduced infarct size (triphenyltetrazolium chloride staining) by 49%. Neither adenosine receptor blockade with 8-(p -sulfophenyl) theophylline nor the free radical scavenger N-2-mercaptopropionyl glycine inhibited the protection triggered by ethanol. In contrast, protein kinase C inhibition with chelerythrine, protein tyrosine kinase inhibition with genistein, and blockade of ATP-sensitive potassium channels (K(ATP)) with either 5-hydroxydecanoate or glibenclamide did abolish protection. Thus, transient ethanol exposure followed by washout prior to ischemia elicits a preconditioning-like effect involving protein kinase C, at least one protein tyrosine kinase, and K(ATP)channels, but neither adenosine nor free radicals.

Menadione mimics the infarct-limiting effect of preconditioning in isolated rat hearts.

The role of mitochondrial free radicals in the cardioprotective effect of ischemic preconditioning was examined in isolated buffer-perfused rat hearts. Infarct size in control rat hearts subjected to 30 min of regional ischemia and 120 min of reperfusion was 32.6 +/- 3.4% of the risk zone. Ischemic preconditioning (3 cycles of 5-min global ischemia/5-min reperfusion) before the same regional ischemia and reperfusion protocol significantly reduced infarct size to 2.6 +/- 0.8% of the risk zone. Perfusion with menadione (3.0 microM), a generator of mitochondrial free radicals, in lieu of preconditioning ischemia significantly reduced infarction to 10.9 +/- 2.7%. N-2-mercaptopropionylglycine (1.0 mM), a free radical scavenger, blocked the protection of menadione, significantly increasing infarction to 23.5 +/- 1.1%. Myxothiazol (0.6 microM), a site III mitochondrial inhibitor, blocked the protection of menadione and significantly increased infarction to 25.2 +/- 3.8%. The infarct-limiting effect of menadione was attenuated to 19.7 +/- 1.5% of the risk zone by 10 microM SB203580, a p38 mitogen-activated protein kinase (MAPK) inhibitor. Furthermore, menadione significantly increased p38 MAPK phosphorylation to a level 5.6-fold over basal. These results indicate that free radicals that originate within mitochondria can activate p38 MAPK and protect hearts against infarction.

Signal characteristics of multichannel epicardial electrograms in chronic ischaemic and scarred myocardium: electromechanical mismatch indicates viability in regions of myocardial dysfunction.

BACKGROUND: To predict the outcome after myocardial revascularisation, a clear separation between hibernation and/or repetitive stunning on the one hand and myocardial scarring on the other hand is of importance. METHODS AND RESULTS: A total of 44 patients was included in this study. In 35 patients with chronic myocardial ischaemia and an indication for coronary bypass-surgery, epicardial mapping of local activation was performed. Nine patients with LV aneurysm and an indication for antitachycardia surgery were also included. For simultaneous recording of the local electrograms during sinus rhythm, a sock electrode with 102 bipolar leads was used. The regional myocardial contraction pattern was assessed from preoperative angiograms and regional myocardial metabolism (viability) from 18F-FDG PET, respectively. The results were projected on the grid of the intraoperative position of the sock electrode. This enabled regional comparison of electrogram characteristics to local contraction patterns and viability. For the characterisation of local electrograms, peak-to-peak amplitude and duration of activation were calculated using custom-made automated computer-algorithms. Dysfunctional but viable areas showed normal or almost normal electrographic signal characteristics. In contrast, dysfunctional and non-viable myocardium showed a distinct reduction of local amplitudes and prolongation of signal duration. These changes were even more intense in areas of LV aneurysms. CONCLUSIONS: In patients with chronic ischaemic myocardium, a mismatch between mechanical function and local electrogram characteristics was observed in areas with preserved metabolism. Thus, normal epicardial electrograms in regions of myocardial dysfunction may be an indicator for myocardial viability.

Acute ethanol exposure fails to elicit preconditioning-like protection in in situ rabbit hearts because of its continued presence during ischemia.

OBJECTIVES: Is the timing of exposure critical for ethanol's ability to induce cardioprotection? BACKGROUND: Acute ethanol exposure has been reported to mimic ischemic preconditioning in vitro, but it failed to protect in situ. We hypothesized that these conflicting findings were related to ethanol's presence during ischemia in situ. METHODS: The effect on infarct size (triphenyltetrazolium chloride) of acute ethanol exposure (0.35, 0.7, and 1.4 g/kg IV) 10 min before ischemia was measured in open-chest rabbits after 30 min of regional ischemia and reperfusion and was compared to ethanol's ability to reduce infarct size in isolated hearts in which the timing of ethanol exposure could be varied. RESULTS: Ethanol exposure in situ shortly before ischemia did not reduce infarct size. Moreover, ethanol abolished protection from both ischemic preconditioning and mitochondrial KATP channel activation. In contrast, in buffer-perfused hearts exposed to 10 to 50 mmol/liter ethanol for 5 min followed by washout before ischemia, infarct size was significantly reduced. When ethanol exposure was prolonged until the end of ischemia in isolated hearts, protection was abolished. Conversely, protection was seen when ethanol was infused in situ followed by removal of the heart and perfusion with ethanol-free buffer prior to ischemia in a Langendorff preparation. When 50 min were allowed to metabolize the ethanol prior to ischemia, protection could also be shown in situ. CONCLUSIONS: Ethanol exposure followed by washout or sufficient time to metabolize the alcohol prior to ischemia induces preconditioning-like myocardial protection. However, if present throughout ischemia, ethanol actually blocks all preconditioning-related protection.

Complement activation and immune complexes in children with polyarticular juvenile rheumatoid arthritis: a longitudinal study.

OBJECTIVE: To determine whether levels of either circulating immune complexes (IC) or complement activation fragments change as disease activity changes in children with polyarticular juvenile rheumatoid arthritis (JRA). METHODS: Twenty-six children with polyarticular JRA were examined over a time course of 4-21 months. Plasma complement activation fragments and IC were measured by commercially available enzyme linked immunoabsorbant assays. RESULTS: Both complement activation fragments and IC levels were lower in individual children when their articular disease was inactive. Children with persistently active disease had no change in any of these measures. CONCLUSION: Elevated levels of plasma IC and complement activation fragments are features of active polyarticular JRA. We believe our data support a role for the complement system in the pathophysiology of polyarticular JRA.

Light-regulated modification and nuclear translocation of cytosolic G-box binding factors in parsley.

Functional cell-free systems may be excellent tools with which to investigate light-dependent signal transduction mechanisms in plants. By evacuolation of parsley protoplasts and subsequent silicon oil gradient centrifugation of lysed evacuolated protoplasts, we obtained a highly pure and concentrated plasma membrane-containing cytosol. Using GT- and G-box DNA elements, we were able to demonstrate a specific localization of a pool of G-box binding activity and factors (GBFs) but not one of GT-box binding activity in this cytosolic fraction. The DNA binding activity of the cytosolic GBFs is modulated in vivo as well as in vitro by light and phosphorylation/dephosphorylation activities. The regulation of cytosolic G-box binding activity by irradiation with continuous white light and phosphorylation correlates with a light-modulated transport of GBFs to the nucleus. This was shown by a GBF-antibody cotranslocation assay in permeabilized, cell-free evacuolated parsley protoplasts. We propose that a light-regulated subcellular displacement of cytosolic GBFs to the nucleus may be an important step in the signal transduction pathway coupling photoreception to light-dependent gene expression.

Two Tcp-1-related but highly divergent gene families exist in oat encoding proteins of assumed chaperone function.

Tcp-1-related sequences have been isolated from a cDNA library of etiolated 6-day-old oat (Avena sativa) seedlings. This attempt was made to obtain cDNAs of a recently published 60 kDa plant chaperone that re-folds denatured phytochrome and which was biochemically characterised as a Tcp-1-related protein [(1993) Nature 363, 644-647]. The translation of the putative coding sequence from one full-length cDNA clone displays no specific homologies to amino acid sequences known from peptide sequencing of the oat 60 kDa chaperone. Antibodies raised against the 60 kDa chaperone and over-expressed protein from one full-length coding sequence for Tcp-1 from oat show no cross-reactivity, whereas a monoclonal antibody raised against mouse Tcp-1 protein recognizes both the 60 kDa protein purified from plant extracts and over-expressed protein from Tcp-1-related cDNA sequences.

Complement activation and immune complexes in juvenile rheumatoid arthritis.

We investigated the potential role of the complement system in juvenile rheumatoid arthritis (JRA) by examining plasma for levels of complement activation fragments C4d and Bb. We correlated findings with both disease activity and laboratory abnormalities, including immune complex (IC) levels. While there was a strong correlation between active disease and both C4d and Bb plasma levels in JRA, no strong correlations could be made between IC levels and complement activation products; weak associations were seen between complement activation fragments and erythrocyte sedimentation rate. Our data suggest that plasma complement activation is a concomitant of active disease in JRA; however, its role in the pathophysiology of JRA remains uncertain.

Detection of IgM rheumatoid factors by enzyme-linked immunosorbent assay in children with juvenile rheumatoid arthritis: correlation with articular disease and laboratory abnormalities.

This study was undertaken to determine the clinical relevance of IgM rheumatoid factors (RFs) detected by enzyme-linked immunosorbent assay (ELISA) in children with juvenile rheumatoid arthritis (JRA) by examining their association with severity of acute articular disease. ELISAs for IgM-RF were performed on serum specimens from 65 children with JRA. Activity of articular disease was estimated by an arbitrary scoring system. Significant differences were seen in articular disease activity between the group of children with polyarticular disease who were IgM-RF-positive by ELISA compared with those who were IgM-RF-negative (P = .0003). When a small group of individual children with polyarticular disease were followed longitudinally, similar correlations were found between severity of acute disease and the presence of IgM-RFs detected by ELISA. In children with pauciarticular JRA, expression of IgM-RFs appeared to be a transient phenomenon with no correlation with either articular disease or laboratory abnormalities.

A nursing diagnosis based model: guiding nursing practice.

Fiscal uncertainty, anxiety about nursing retention, and public scrutiny characterize the hospital milieu. During times such as these, introducing a conceptual model may appear inpractical and untimely. However, the conceptual model at Robert Wood Johnson University Hospital has demonstrated many practical applications. It guides nursing practice and provides a framework for quality assurance, documentation of nursing care, and education of nurses in the hospital. Future plans include using the model as a basis for developing a computerized care planning system and a method for cost accounting for nursing. The authors describe how the model serves to unify, give direction, simplify, and improve nursing practice.

[Peri-implantation enzymes and mineralization in bone tissue after implantation of bioactive vitroceramic material--a method for biomaterial testing for hard tissue substitutes. 2. Results of studies of vitroceramics and their modification by the admixture of metal oxides]. / Untersuchungen periimplantärer Enzymaktivitäten und der periimplantären Mineralisation im Knochengewebe nach Implantation bioaktiver vitrokeramischer Materialien--Eine Methode der Biomaterialprüfung für den Hartgewebeersatz. Teil 2: Ergebnisse der Untersuchungen von Vitrokeramen und deren Modifizierungen durch Zusatz von Metalloxiden.

The activities of the alkaline and the acid bone phosphatases as well as the concentrations of calcium and phosphorus were measured in the periimplantal tissue of the rat femur bone after implantation of the vitroceramic Ap 40, the metal oxide stabilized vitroceramics Ap 40 A and Ap 40 Z, as well titanium after 2, 10, and 15 weeks. The incorporation of the vitroceramic Ap 40 turns out like a primary bone fracture healing. The implants Ap 40 A and Ap 40 Z are a compromise with a higher stability and the osteogenesis induced effect is preserved, but is belated in contrast to Ap 40.

[Peri-implant enzyme activities and mineralization in bone tissue after implantation of bioactive vitroceramics--a method for biomaterial testing of hard-tissue substitutes. 1. Establishment and representation of the method]. / Untersuchungen periimplantärer Enzymaktivitäten und der periimplantären Mineralisation im Knochengewebe nach Implantation bioktiver vitrokeramischer Materialien--Eine Methode der Biomaterialprüfung für den Hartgewebeersatz. Teil 1: Begründung und Darlegung der Methodik.

A method for testing the bioactivity of hard tissue implants is described by analysis of the periimplantary enzyme activities of the alkaline and the acid phosphatase in the femur of rats. Bioactive materials cause an increase of the activity of the alkaline phosphatase in the periimplantal bone tissue. An increase of the activity of the acid phosphatase is a measure for the biodepressive effect of the implant material.