Combined systemic thrombolysis with alteplase and early hyperbaric oxygen therapy in experimental embolic stroke in rats: relationship to functional outcome and reduction of structural damage

INTRODUCTION

The only causal therapy in ischemic stroke is thrombolysis with recombinant tissue plasminogen activator (rtPA), but it is feasible only for few patients, and new therapies are needed. This study investigates the effects of systemic thrombolysis with rtPA combined with hyperbaric oxygen therapy (HBOT) in embolic stroke in rats.

METHODS

In 22 male Wistar rats, an embolic ischemic stroke was induced. The animals were randomized to one of four groups: control, thrombolysis alone, HBOT sequential or HBOT parallel with thrombolysis. HBOT (2.4 ATA, 1 h) started 45 min (sequential) or 120 min (parallel) after stroke. rtPA was given intravenously 120 min after stroke onset. Functional tests were performed after stroke induction and after treatment. After 6 h infarct volume and intracerebral hemorrhagic complications were assessed.

RESULTS

Compared to the control group only the combination of HBOT and thrombolysis significantly improved the functional outcome (p=0.03) and reduced the infarct volume (p=0.01), whereas thrombolysis alone did not show a significant benefit. In all treatment groups there was a trend towards fewer hemorrhagic transformations.

CONCLUSION

Hyperbaric oxygen in combination with thrombolysis shows neuroprotection in acute ischemic stroke in rats by reducing infarct volume and improving functional outcome in the early poststroke period.

Efficient atmospheric cleansing of oxidized organic trace gases by vegetation

The biosphere is the major source and sink of nonmethane volatile organic compounds (VOCs) in the atmosphere. Gas-phase chemical reactions initiate the removal of these compounds from the atmosphere, which ultimately proceeds via deposition at the surface or direct oxidation to carbon monoxide or carbon dioxide. We performed ecosystem-scale flux measurements that show that the removal of oxygenated VOC via dry deposition is substantially larger than is currently assumed for deciduous ecosystems. Laboratory experiments indicate efficient enzymatic conversion and potential up-regulation of various stress-related genes, leading to enhanced uptake rates as a response to ozone and methyl vinyl ketone exposure or mechanical wounding. A revised scheme for the uptake of oxygenated VOCs, incorporated into a global chemistry-transport model, predicts appreciable regional changes in annual dry deposition fluxes.

Carbon isotope analysis of acetaldehyde emitted from leaves following mechanical stress and anoxia

Although the emission of acetaldehyde from plants into the atmosphere following biotic and abiotic stresses may significantly impact air quality and climate, its metabolic origin(s) remains uncertain. We investigated the pathway(s) responsible for the production of acetaldehyde in plants by studying variations in the stable carbon isotope composition of acetaldehyde emitted during leaf anoxia or following mechanical stress. Under an anoxic environment, C3 leaves produced acetaldehyde during ethanolic fermentation with a similar carbon isotopic composition to C3 bulk biomass. In contrast, the initial emission burst following mechanical wounding was 5-12 per thousand more depleted in (13)C than emissions under anoxia. Due to a large kinetic isotope effect during pyruvate decarboxylation catalysed by pyruvate dehydrogenase, acetyl-CoA and its biosynthetic products such as fatty acids are also depleted in (13)C relative to bulk biomass. It is well known that leaf wounding stimulates the release of large quantities of fatty acids from membranes, as well as the accumulation of reactive oxygen species (ROS). We suggest that, following leaf wounding, acetaldehyde depleted in (13)C is produced from fatty acid peroxidation reactions initiated by the accumulation of ROS. However, a variety of other pathways could also explain our results, including the conversion of acetyl-CoA to acetaldehyde by the esterase activity of aldehyde dehydrogenase.

Chemical sensing of plant stress at the ecosystem scale

Abstract. Significant ecosystem-scale emissions of methylsalicylate (MeSA), a semivolatile plant hormone thought to act as the mobile signal for systemic acquired resistance (SAR), were observed in an agroforest. Our measurements show that plant internal defence mechanisms can be activated in response to temperature stress and are modulated by water availability on large scales. Highest MeSA fluxes (up to 0.25 mg/m2/h) were observed after plants experienced ambient night-time temperatures of ~7.5°C followed by a large daytime temperature increase (e.g. up to 22°C). Under these conditions estimated night-time leaf temperatures were as low as ~4.6°C, likely inducing a response to prevent chilling injury. Our observations imply that plant hormones can be a significant component of ecosystem scale volatile organic compound (VOC) fluxes (e.g. as high as the total monoterpene (MT) flux) and therefore contribute to the missing VOC budget. If generalized to other ecosystems and different types of stresses these findings suggest that semivolatile plant hormones have been overlooked by investigations of the impact of biogenic VOCs on aerosol formation events in forested regions. Our observations show that the presence of MeSA in canopy air serves as an early chemical warning signal indicating ecosystem-scale stresses before visible damage becomes apparent. As a chemical metric, ecosystem emission measurements of MeSA in ambient air could therefore support field studies investigating factors that adversely affect plant growth.

Microbial risk factors of cardiovascular and cerebrovascular diseases: potential therapeutical options

Infection and inflammation may have a crucial role in the pathogenesis of atherosclerosis. This hypothesis is supported by an increasing number of reports on the interaction between chronic infection, inflammation, and atherogenesis. Assessment of serological and inflammatory markers of infection may be useful adjuncts in identifying those patients who are at a higher risk of developing vascular events, and in whom more aggressive treatments might be warranted.

Characterization of the molecular interaction between caveolin-1 and the P2X receptors 4 and 7 in E10 mouse lung alveolar epithelial cells

P2X(4) and P2X(7) receptors are abundantly expressed in alveolar epithelial cells, and are thought to play a role in regulating fluid haemostasis. Here, we analyzed the expression and localization of the P2X(4)R, and characterized the interaction between Cav-1 and both P2X(4)R and P2X(7)R in the mouse alveolar epithelial cell line E10. Using the biotinylation assay, we found that only glycosylated P2X(4)R is exposed at the cell surface. Triton X-100 solubility experiments and sucrose gradient centrifugation revealed that P2X(4)R was partially localized in Cav-1 rich membrane fractions. Cholesterol depletion with Mbeta-CD displaced Cav-1 and P2X(4)R from the low-density to the high-density fractions. Suppression of Cav-1 protein expression using short hairpin RNAs resulted in a large reduction in P2X(4)R levels. Double immunofluorescence showed that P2X(4)R and Cav-1 partially colocalize in vitro. Using the GST pull-down assay, we showed that Cav-1 interacts in vitro with both P2X(4)R and P2X(7)R. Co-immunoprecipitation experiments confirmed the interaction between P2X(7)R and Cav-1. ATP stimulation increased the level of P2X(4)R in the lipid raft/caveolae fraction, whereas Cav-1 content remained constant. Our results support recent evidence that P2X receptors are present in both raft and non-raft compartments of the plasma membrane and thus exhibit variable ATP sensitivity.

Effect of the green tea polyphenol epigallocatechin gallate (EGCG) on growth and IL-6 signalling pathways in malignant plasma cells

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Background: Epigallocatechin gallate (EGCG) is the predominant polyphenolic constituent of green tea leaves that possesses antitumor, antiinflammatory, and antioxidant activity. EGCG exerts its effects through potentially multiple mechanisms including inhibition of growth factor receptor signalling. The compound is currently under investigation in a phase I/II clinical trial for treatment of patients with early stage chronic lymphocytic leukemia at Mayo Clinic. The goal of our study was to examine the in vitro effects of EGCG in multiple myeloma (MM). Methods: A panel of human myeloma cell lines (n=6) including the IL-6 dependent INA-6 cell line was used to evaluate the sensitivity to EGCG. Cells were cultured for three days in the absence or presence of EGCG at concentrations between 6.25 μM and 100 μM. Cell viability was determined in a colorimetric tetrazolium (MTS) based assay and by trypanblue exclusion. For signalling experiments, INA-6 cells were IL-6 and serum starved and then treated with EGCG for two hours before IL-6 was added. Whole cell lysates were prepared and subjected to SDS-PAGE and Western blot analysis. Results: EGCG inhibited the in vitro growth of human myeloma cell lines by inducing cell death in a time and dose-dependent manner. IC50 concentrations were between 12,5 μM and 50 μM. IL-6 mediated growth of INA-6 cells was inhibited at similar doses. The addition of excess amounts of IL-6 could not protect from EGCG induced cytotoxicity. Pretreatment of INA-6 cells with EGCG resulted in a dose-dependent inhibition of IL-6 induced STAT3 tyrosine phosphorylation. In these cells, stimulation with IL-6 leads to upregulation of Mcl-1 expression. In contrast, phosphorylation of p44/p42 MAPK, which is constitutively activated in INA-6 cells, was not affected. Conclusion: EGCG has growth inhibitory activity on myeloma cells. Specific inhibition of signalling pathways that regulate expression of anti-apoptotic proteins could be one mechanism how EGCG exerts its activity. Our work provides the rationale for further studies to evaluate the effect of EGCG not only in B-CLL, but also in plasma cell tumors.

No significant financial relationships to disclose.

Caveolin-1 influences P2X7 receptor expression and localization in mouse lung alveolar epithelial cells

The P2X7 receptor has recently been described as a marker for lung alveolar epithelial type I cells. Here, we demonstrate both the expression of P2X7 protein and its partition into lipid rafts in the mouse lung alveolar epithelial cell line E10. A significant degree of colocalization was observed between P2X7 and the raft marker protein Caveolin-1; also, P2X7 protein was associated with caveolae. A marked reduction in P2X7 immunoreactivity was observed in lung sections prepared from Caveolin-1-knockout mice, indicating that Caveolin-1 expression was required for full expression of P2X7 protein. Indeed, suppression of Caveolin-1 protein expression in E10 cells using short hairpin RNAs resulted in a large reduction in P2X7 protein expression. Our data demonstrate a potential interaction between P2X7 protein and Caveolin-1 in lipid rafts, and provide a basis for further functional and biochemical studies to probe the physiologic significance of this interaction.

Cellular origin of pro-coagulant and (anti)-fibrinolytic factors in bleomycin-injured lungs

Excessive pro-coagulant and decreased fibrinolytic activities in the alveolar compartment have been repeatedly documented for inflammatory and fibrotic lung diseases. The current authors determined the contribution of different resident lung cells to the altered local production of coagulation- and fibrinolysis-system components in bleomycin-injured mouse lungs via cell-specific and quantitative assessment of mRNA levels of various pro-coagulant and (anti)-fibrinolytic factors. Laser-assisted microdissection technology was used to sample specific cell populations in combination with subsequent mRNA analysis by real-time quantitative reverse transcriptase-PCR. Additionally, western blot analysis, immunohistochemistry and activity assays were performed. Following bleomycin challenge, the strongest induction of tissue factor and plasminogen activator inhibitor (PAI)-1 mRNA expression was observed in alveolar macrophages (approximately 250- and 60-fold induction, respectively). These factors were also upregulated in alveolar type II cells, but to an approximately six-fold lesser extent. In contrast, PAI-2 expression was induced exclusively in alveolar macrophages. A slight increase of urokinase-type plasminogen activator (uPA) expression was also observed in alveolar macrophages (two-fold induction), but uPA activity was reduced due to a disproportionate increase of PAI production. Alveolar macrophages and, to a lesser extent, alveolar type II cells are the main sources of locally produced pro-coagulant and anti-fibrinolytic factors in bleomycin-injured lungs.

Surfactant protein C mutations in sporadic forms of idiopathic interstitial pneumonias

Interstitial pneumonias have recently been associated with mutations in the gene encoding surfactant protein C (SFTPC). In particular, SFTPC mutations have been reported in a number of familial forms of pulmonary fibrosis and in infants with interstitial lung diseases. The present study searched for SFTPC mutations in adult patients with sporadic idiopathic interstitial pneumonia. In total, 35 adult patients with sporadic idiopathic interstitial pneumonia and 50 healthy subjects were investigated for SFTPC mutations by direct DNA sequencing. Of the patients with sporadic idiopathic interstitial pneumonia, 25 suffered from idiopathic pulmonary fibrosis and 10 patients from nonspecific interstitial pneumonia. Only two frequent nonsynonymous variants, T138N and S186N, were detected. Allele frequencies of both variations as well as of other identified noncoding alterations did not differ significantly between the diverse patient groups and control subjects. In conclusion, mutations in the gene encoding surfactant protein C are not common in sporadic cases of idiopathic pulmonary fibrosis and nonspecific interstitial pneumonia, suggesting that the mutated gene does not play an important role in the pathogenesis of these forms of idiopathic interstitial pneumonia.

Antiepileptic drugs for the primary and secondary prevention of seizures after intracranial venous thrombosis

BACKGROUND

Intracranial venous thrombosis (ICVT) commonly presents with seizures in the acute period, and some patients may develop recurrent seizures in the long term. The prophylactic use of antiepileptic drugs (AEDs) for the management of post-ICVT seizures is controversial and there is currently no consensus on the optimal management of post-ICVT seizures.

OBJECTIVES

To assess the effects of AEDs for the primary and secondary prevention of seizures related to ICVT.(1) Do AEDs reduce the likelihood of seizures in patients who have had an ICVT but have not had a seizure?(2) Do AEDs reduce the likelihood of further seizures in patients who have had an ICVT and at least one seizure?

SEARCH STRATEGY

We aimed to identify relevant studies in the Cochrane Epilepsy Group and Cochrane Stroke Group Trials Registers. We also undertook specialised searches of the Cochrane Central Register of Controlled Trials (CENTRAL) and MEDLINE, and checked the reference lists of articles retrieved from the searches.

SELECTION CRITERIA

We considered all randomised and quasi-randomised controlled trials in which patients were assigned to a treatment group (that is, receiving at least one AED) or control group (receiving placebo or no drug).

DATA COLLECTION AND ANALYSIS

Both review authors independently screened and assessed the methodological quality of the studies. If studies had been included, then one review author would have extracted the data and the other would have checked the extracted data.

MAIN RESULTS

No relevant studies were found.

AUTHORS' CONCLUSIONS

There is no evidence to support or refute the use of antiepileptic drugs for the primary or secondary prevention of seizures related to intracranial venous thrombosis. Well-designed randomised controlled trials are urgently needed to inform practice.

Early biochemical and histological alterations in rat corticoencephalic cell cultures following metabolic damage and treatment with modulators of mitochondrial ATP-sensitive potassium channels

The present study was aimed at characterizing alterations of the nucleotide content and morphological state of rat corticoencephalic cell cultures subjected to metabolic damage and treatment with modulators of mitochondrial ATP-dependent potassium channels (mitoK(ATP)). In a first series of experiments, in vitro ischemic changes of the contents of purine and pyrimidine nucleoside diphosphates and triphosphates were measured by high performance liquid chromatography (HPLC) and the corresponding histological alterations were determined by celestine blue/acid fuchsin staining. As an ischemic stimulus, incubation with a glucose-free medium saturated with argon was used. Ischemia decreased the levels of adenosine, guanine and uridine triphosphate (ATP, GTP, UTP) and increased the levels of the respective dinucleotides ADP and UDP, whereas the GDP content was not changed. Both 5-hydroxydecanoate (5-HD) and diazoxide failed to alter the contents of nucleoside diphosphates and triphosphates, when applied under normoxic conditions. 5-HD (30 microM) prevented the ischemia-induced changes of nucleotide and nucleoside levels. Diazoxide (300 microM), either alone or in combination with 5-hydroxydecanoate (30 microM) was ineffective. Pyruvate (5 mM) partially reversed the effects of ischemia or ischemia plus 2-deoxyglucose (20mM) in the incubation medium. Diazoxide (300 microM) and 5-HD (30 microM) had no effect in the presence of pyruvate (5mM) and 2-deoxyglucose (20mM). Staining the cells with celestine blue/acid fuchsin in order to classify them as intact, reversibly or profoundly injured, revealed a protective effect of 5-HD. When compared with 5-HD, diazoxide, pyruvate and 2-deoxyglucose had similar but less pronounced effects. In conclusion, these results suggest a protective role of 5-hydroxydecanoate on early corticoencephalic nucleotide and cell viability alterations during ischemia.

Gp130 and ras mediated signaling in human plasma cell line INA-6: a cytokine-regulated tumor model for plasmacytoma

INTRODUCTION

Cytokines of the gp130-family, particularly interleukin(IL)-6, play a crucial role in the propagation of malignant plasma cells.

MATERIALS AND METHODS

The role of IL-6 and other gp130-cytokines was studied in the human plasma cell line INA-6 in vitro and in INA-6 xenografts. The proliferative response to gp130-cytokines was evaluated and activated components of gp130-signaling pathways were identified by Western blotting and DNA binding studies. Specifically, expression of IL-6 and receptors for IL-6 and leukemia inhibitory factor were analysed by RT-PCR and ELISA.

RESULTS

The plasma cell line INA-6 was cultured for several years remaining strictly dependent on exogenous IL-6. Other gp130-cytokines had no significant effect on INA-6 cell proliferation in vitro. Due to an activating mutation in the N-ras gene, mitogen-activated protein kinases (MAPK) were constitutively phosphorylated. In contrast, signal transducer and activator of transcription(STAT)-3 activation was dependent on stimulation with IL-6. Blocking of either one of these pathways resulted in a significant decrease of INA-6 cell proliferation. Remarkably, INA-6 xenografts did not require exogeneous IL-6 for proliferation in vivo. Instead, an autocrine IL-6 loop and, in certain tumor sublines, responsiveness to additional gp130-cytokines was induced during in vivo growth.

CONCLUSION

Activation of the gp130 signal transducer is mandatory for INA-6 cell growth in vitro and in vivo. Both the MAPK and the Jak/STAT pathway are operative in malignant plasma cells and either one is essential for plasma cell growth. The INA-6 cell line provides a preclinical model to study growth regulation of human plasmacytoma cells and to evaluate novel therapeutic strategies.

Canopy level fluxes of 2-methyl-3-buten-2-ol, acetone, and methanol by a portable relaxed eddy accumulation system

Canopy level flux measurements of 2-methyl-3-buten-2-ol (MBO), acetone, and methanol were made over a subalpine forest in the Rocky Mountains in Colorado in the summer of 1999. The measurements were carried out using a portable relaxed eddy accumulation system that collected samples on adsorbent cartridges. Midday fluxes of acetone were highest at approximately 2.5 mg of C m-2 h-1. Methanol and MBO fluxes were approximately 1.0 mg of C m-2 h-1 each. These fluxes occurred with average daytime high temperatures of only 18 degrees C. Diurnal fluxes of MBO were strongly correlated with light and temperature. Acetone and methanol did not have simple diurnal patterns. These results indicate that oxygenated volatile organic compounds may make a significant contribution to the flux of reactive carbon to the atmosphere in western U.S. pine forests.