Airtight Chamber Research Articles

The effects of amiloride and age on oxygen consumption coupled to electrogenic sodium transport in the human sigmoid colon.

Background/Aim:Aerobic metabolism is necessary for ion transport in many transporting epithelia, including the human colonic epithelium. We assessed the effects of the epithelial sodium channel blocker, amiloride, on oxygen consumption and short-circuit current of the human sigmoid epithelium to determine whether these effects were influenced by the age of the subject.Materials and Methods:Segments of the sigmoid colon were obtained from the safety margin of resections performed in patients of 62–77 years of age. Isolated mucosa preparations were obtained and mounted in airtight Ussing chambers, fit for simultaneous measurement of short-circuit current and oxygen concentration, before and after blocking epithelial sodium channels with amiloride (0.1 mmol/L). Regression analyses were performed to assess the associations between short-circuit current, oxygen consumption, and age of the subject as well as to define the relationship between the decreases in short-circuit current and oxygen consumption after blockade.Results:Epithelial sodium channel blockade caused an 80% reduction in short-circuit current and a 26% reduction in oxygen consumption. Regression analysis indicated that both changes were significantly related (r = 0.884; P = 0.0007). Oxygen consumption decreased by 1 μmol/h/cm2 for each 25 μA/cm2 decrease in short-circuit current. Neither short-circuit current nor oxygen consumption had any significant relationship with the age of the subjects.Conclusion:The decrease in epithelial oxygen consumption caused by amiloride is proportional to the decrease in short-circuit current and independent of the age of the subject.

How to enhance experience and skill of non invasive ventilation: suggestions from the literature

19 have seen an iron lung, yet sixty years ago these medical mechanical monsters would have been a common sight in most hospital throughout the world. Through the late 1920’s and into 50’s the iron lung was considered to be state of the art, high-tech, life support technology. Indeed medical physician of the time would have learn about such devices as a recommended treatment for respiratory paralysis, used to maintain life for those whose breathing capabilities had been impaired or destroyed by poliomyelit is (1).They were non invasive in the sense that no part of the device penetrated the patient. In truth, it was the patient who was inside the machine. The whole body was enclosed within the air tight chamber of the device, apart from the head which protruded through a tight seal around the neck (Figure 1). For each inspiration a large set of leather bellows mounted in a separate pump unit would expand causing the pressure within the cabinet to be lowered to below that of the surrounding atmosphere. The sub-atmospheric pressure in turn acted upon the chest, causing it to expand, thereby drawing fresh air into the lungs through the patients’ mouth. During expiration, the pressure equalise to atmospheric and the patient exhals passively. This method of artificial respiration was known as external negative pressure ventilation (ENPV). The first description of ventilator support via mouthpiece was described by Dr.Affeldt of Rancho Los Amigos in 1953 (Figure 2), to assist patients when the iron lung was open for patient care (1, 2). He observed that intermittent positive pressure administered by a circuit with a mouthpiece could be used to relieve dyspnea in patients with polio ventilator-dependence when negative pressure ventilation had been interrupted for transfers, nursing or physical therapy (1, 2). However, intermittent positive pressure breathing (IPPB) machine became available even earlier than 1951 and a positive pressure blower caller was used to deliver occasional deep breaths as well. Patients used mouthpiece NIV in a wheelchair as well as use an intermittent abdominal pressure ventilator (IAPV) or other portable negative pressure ventilators. Since IPPV via mouthpiece Bantam became available and since the IPPV via mouthpiece was able to provides much larger volumes of air directly to the lungs than the IAPV, it became the principal mode of ventilatory support during lung infections and other conditions of lung impairment. The mouthpieces were mounted on the controls of powered Mini-review

Improving indoor oxygen in residential buildings using houseplants

Cities need more trees and plants. People are getting tired of cities without them. They want pretty flora that will attract fauna. Plants growing should be made a legal commitment for industries as well as household level. Everyone should involve and encourage population, to generate love for the plants and trees. Cool greenery pleases the human eye and soothes the mind. Moreover, the cleansing of the environment needs the planting of trees, shrubs and plants as these replenish oxygen in the atmosphere, so essential for human life. Though it is not possible for everyone to plan something for global environment, but small contributions should definitely be made by individuals. So, the study was carried out to aware the people that plants help in maintaining the purity of indoor environmental status by enhancing the oxygen level. Results entailed that houseplants performed their best, whenever they were utilized, either indoor or outdoor by releasing O2 and making the IAQ fresh and pure. However, plants perform better in enclosed and air tight chambers, as the rooms without any ventilation require fresh air, which plants do by releasing O2.

El método de microdifusión de Conway. Su aplicación en el dosaje de amoniaco, urea y nitrógeno no protéico

El método de microdifusión de Conway, utilizando un sistema de cámara cerrada, permite la determinación de sustancias susceptibles de volatilización y fijación en medio apropiado. Dicho sistema comprende dos compartimentos ubicados de modo que, si en uno de ellos colocamos la sustancia a volatilizar y en el otro un fijador o atrapador adecuado, al hacer hermética la cámara se establecerá una corriente del gas desde el área de su liberación hacia la de su fijación; corriente que estará dada por el simple juego de las diferencias de tensión del gas en ambas superficies. El cuerpo así aislado es, después, analizado cuantitativamente por titulación, potenciometría, fotocolorimetría, etc.

Imaging of oxygen transmission in the oak wood of wine barrels using optical sensors and a colour camera

Background and Aims Wine ageing in oak barrels is characterised by a series of physical and chemical processes, in many of which oxygen plays an important role. Therefore, to control better this phase of winemaking, it is not enough to know that oxygen penetrates into the barrel through the oak wood; it is also important to know how oxygen moves through the wood into the barrel, in what quantity and which factors are involved. Methods and Results We attempted to answer these questions with a high-resolution colour camera, ratiometric calibration and a planar optode with which the two-dimensional distribution and dynamics of oxygen within an oak barrel stave were studied. It was possible to make two-dimensional measurements when combined with microscopic optics and an appropriate camera, which permitted the measure of the transmission of oxygen into the barrel through the oak stave and the study of the mechanism of transmission. The trial was applied to both dry and wet oak wood, which revealed how the moisture content of the wood influenced oxygen transmission. The measurements were made in an airtight chamber under controlled temperature and pressure, which accurately reproduced the conditions of a stave in an oak wood barrel filled with liquid. Conclusion We were able to visualise the diffusion of oxygen in both dry and in wet French oak wood under conditions similar to those operating in a barrel. The moisture content of the wood influenced the oxygen transmission rate (OTR) through the wood. Significance of the Study For the first time, the dissolved oxygen dynamics and two-dimensional distribution of oxygen within the thickness of a barrel stave have been demonstrated. Wood water saturation is a key factor in the diffusion of oxygen through wood with barrel OTR decreasing during the ageing period.

Conjugate heat transfer analysis of an ultrasonic molten metal treatment system

In piezoceramic ultrasonic devices, the piezoceramic stacks may fail permanently or function improperly if their working temperatures overstep the Curie temperature of the piezoceramic material. While the end of the horn usually serves near the melting point of the molten metal and is enclosed in an airtight chamber, so that it is difficult to experimentally measure the temperature of the transducer and its variation with time, which bring heavy difficulty to the design of the ultrasonic molten metal treatment system. To find a way out, conjugate heat transfer analysis of an ultrasonic molten metal treatment system is performed with coupled fluid and heat transfer finite element method. In modeling of the system, the RNG model and the SIMPLE algorithm are adopted for turbulence and nonlinear coupling between the momentum equation and the energy equation. Forced air cooling as well as natural air cooling is analyzed to compare the difference of temperature evolution. Numerical results show that, after about 350 s of working time, temperatures in the surface of the ceramic stacks in forced air cooling drop about 7 K compared with that in natural cooling. At 240 s, The molten metal surface emits heat radiation with a maximum rate of about 19 036 W/m2, while the heat insulation disc absorbs heat radiation at a maximum rate of about 7922 W/m2, which indicates the effectiveness of heat insulation of the asbestos pad. Transient heat transfer film coefficient and its distribution, which are difficult to be measured experimentally are also obtained through numerical simulation. At 240 s, the heat transfer film coefficient in the surface of the transducer ranges from −17.86 to 20.17 W/(m2 · K). Compared with the trial and error method based on the test, the proposed research provides a more effective way in the design and analysis of the temperature control of the molten metal treatment system.

Development of a self-cleaning dispersion and exposure chamber: Application to the monitoring of simulated accidents involving the generation of airborne nanoparticles

The release of hazardous nanoparticulate matter in accidental situations was simulated in a specially designed 13-m3 stainless steel airtight chamber, which allowed the dispersion analysis of airborne matter in a practically particle-free environment (less than 2 #/cm3) and in presence of background atmospheric aerosols. A fast recovering of the initial situation was achieved by means of a tandem HEPA-filtered air and deionized water system. Both unintended spilling of silica-based nanoparticulate powders and continuous emission of 100-nm SiO2 nanoparticles were used as aerosol generation events. The emission of airborne nanoparticles was analyzed in terms of particle number concentrations (PNC), size distributions and source strengths. The emission of nanoparticulate aerosols reached peak PNC for particles in the range from 5nm to 1μm with source strengths about 108 #/h in a background-filled environment and 1010 #/h in a practically particle-free atmosphere. No agglomeration was noticed for the released nanoparticles, suggesting that PNC was low enough to prevent coagulation and that particle diameters were over 80nm. Results indicate that emitted matter was within the range of the most penetrating particle sizes and with source strengths similar to accidental scenarios.

A Novel Root System for Simulating Transpiration-Induced Soil Suction in Centrifuge

Plant transpiration has potential beneficial effects to slope stability because it increases soil suction, which results in not only an increase in shear strength but also a decrease in water permeability. Although the effects of vegetation on slope stability have been recently investigated using centrifuge, contributions of plant-induced suction are ignored. In order to simulate transpiration-induced suction in a centrifuge model test, a novel root system that enables suction to be induced and controlled at high-g are developed and verified in this study. This new root system consists of a high air-entry value (AEV) porous filter, cellulose acetate, which has scaled mechanical properties, including tensile strength, elastic modulus, and axial rigidity, similar to living roots. This filter is fully saturated with de-aired water and it is connected to an airtight chamber for controlling vacuum pressures. The function of the water-saturated porous filter is to maintain hydraulic gradient between soil and the root system for any vacuum pressure lower than the AEV of the filter. Any reduction of soil moisture due to applied vacuum hence induces suction. Suctions induced by the new root system were verified to be consistent with those induced by a living tree (Schefflera heptaphylla) at 1-g and that retained by vegetation in the field. Both vertical and horizontal influence zones of suction of the living tree were captured. For centrifuge tests carried out at 15-g, suctions of up to 25 kPa can be simulated.

Perinatal hypoxia: different effects of the inhibitors of GABA transporters GAT1 and GAT3 on the initial velocity of [3H]GABA uptake by cortical, hippocampal, and thalamic nerve terminals.

AimTo analyze the effects of highly selective blocker GAT1, NO-711, and substrate inhibitor GAT3, β-alanine, on the initial velocity of [3H]GABA uptake by cortical, hippocampal, and thalamic nerve terminals (synaptosomes) after perinatal hypoxia.MethodsAnimals were divided into two groups: control (n = 17) and hypoxia (n = 12). Rats in the hypoxia group underwent hypoxia and seizures (airtight chamber, 4% O2 and 96% N2) at the age of 10-12 postnatal days and were used in the experiments 8-9 weeks after hypoxia.ResultsIn cortical synaptosomes, the effects of NO-711 (30 μΜ) and β-alanine (100 μΜ) on [3H]GABA uptake were similar in control and hypoxia groups. In hippocampal synaptosomes, NO-711 inhibited 84.3% of the initial velocity of [3H]GABA uptake in normal conditions and 80.1% after hypoxia, whereas the effect of β-alanine was increased after hypoxia from 14.4% to 22.1%. In thalamic synaptosomes, the effect of NO-711 was decreased by 79.6% in controls and by 70.9% in hypoxia group, whereas the effect of β-alanine was increased after hypoxia from 20.2% to 30.2%.ConclusionsThe effectiveness of β-alanine to influence GABA uptake was increased in hippocampal and thalamic nerve terminals as a result of perinatal hypoxia and the effectiveness of NO-711 in thalamic nerve terminals was decreased. These results may indicate changes in the ratio of active GAT1/GAT3 expressed in the plasma membrane of nerve terminals after perinatal hypoxia. We showed a possibility to modulate non-GAT1 GABA transporter activity in different brain regions by exogenous and endogenous β-alanine.

Preconditioning of Mesenchymal Stem Cells by Sevoflurane to Improve Their Therapeutic Potential

BackgroundBone marrow mesenchymal stem cells (MSCs) have been found to produce beneficial effects on ischemia-reperfusion injury. However, most of the MSCs died when transplanted into the ischemic tissue, which severely limit their therapeutic potential.MethodsUsing an in vitro model of hypoxia and serum deprivation (H/SD), we investigated the hypothesis that sevoflurane preconditioning could protect MSCs against H/SD-induced apoptosis and improve their migration, proliferation, and therapeutic potential. The H/SD of MSCs and neuron-like PC12 cells were incubated in a serum-free medium and an oxygen concentration below 0.1% for 24 h. Sevoflurane preconditioning was performed through a 2-h incubation of MSCs in an airtight chamber filled with 2 vol% sevoflurane. Apoptosis of MSCs or neuron-like PC12 cells was assessed using Annexin V-FITC/propidium iodide (PI). Furthermore, the mitochondrial membrane potential was assessed using lipophilic cationic probe. The proliferation rate was evaluated through cell cycle analysis. Finally, HIF-1α, HIF-2α, VEGF and p-Akt/Akt levels were measured by western blot.ResultsSevoflurane preconditioning minimized the MSCs apoptosis and loss of mitochondrial membrane potential. Furthermore, it increased the migration and expression of HIF-1α, HIF-2α, VEGF, and p-Akt/Akt, reduced by H/SD. In addition, neuron-like PC12 cells were more resistant to H/SD-induced apoptosis when they were co-cultured with sevoflurane preconditioning MSCs.ConclusionThese findings suggest that sevoflurane preconditioning produces protective effects on survival and migration of MSCs against H/SD, as well as improving the therapeutic potential of MSCs. These beneficial effects might be mediated at least in part by upregulating HIF-1α, HIF-2α, VEGF, and p-Akt/Akt.

Comparison of lignin derivatives as substrates for laccase-catalyzed scavenging of oxygen in coatings and films

BackgroundLignin derivatives are phenylpropanoid biopolymers derived from pulping and biorefinery processes. The possibility to utilize lignin derivatives from different types of processes in advanced enzyme-catalyzed oxygen-scavenging systems intended for active packaging was explored. Laccase-catalyzed oxidation of alkali lignin (LA), hydrolytic lignin (LH), organosolv lignin (LO), and lignosulfonates (LS) was compared using oxygen-scavenging coatings and films in liquid and gas phase systems.ResultsWhen coatings containing lignin derivatives and laccase were immersed in a buffered aqueous solution, the oxygen-scavenging capability increased in the order LO < LH < LA < LS. Experiments with coatings containing laccase and LO, LH or LA incubated in oxygen-containing gas in air-tight chambers and at a relative humidity (RH) of 100% showed that paperboard coated with LO and laccase reduced the oxygen content from 1.0% to 0.4% during a four-day period, which was far better than the results obtained with LA or LH. LO-containing coatings incubated at 92% RH also displayed activity, with a decrease in oxygen from 1.0% to 0.7% during a four-day period. The oxygen scavenging was not related to the content of free phenolic hydroxyl groups, which increased in the order LO < LS < LH < LA. LO and LS were selected for further studies and films containing starch, clay, glycerol, laccase and LO or LS were characterized using gel permeation chromatograpy, dynamic mechanical analysis, and wet stability.ConclusionsThe investigation shows that different lignin derivatives exhibit widely different properties as a part of active coatings and films. Results indicate that LS and LO were most suitable for the application studied and differences between them were attributed to a higher degree of laccase-catalyzed cross-linking of LS than of LO. Inclusion in active-packaging systems offers a new way to utilize some types of lignin derivatives from biorefining processes.

Effect of Storage Temperatures on Respiration of Moringa Pods (PKM-1)

Information on the respiration rate of moringa is essential in designing suitable packaging and storage systems for moringa. Air tight PVC chambers of size (70 x 15cm) to hold one kg of moringa (PKM-1)were used to study the respiration rate at three temperatures namely 14, 21 and 28°C. Generally there was progressive reduction of O2 concentration and a steady increase in CO2 concentration, in all tests. The respiration rate of oxygen was 8.75 ml kg -1hr -1at 14ºC, 12.01 ml kg -1hr -1at 21ºC and 66.04 ml kg -1hr -1at 28ºC. The respiration rate of carbon dioxide was 8.31 ml kg -1hr -1at 14ºC, 12.01 ml kg -1hr -1at 21ºC and 34.61ml kg -1hr -1at 28ºC. There was a 1.5 fold increase in respiration as measured by the value of respiration rate of oxygen from 14 to 21ºC and a four fold increase in respiration from 14 to 28ºC.

English

An experiment was conducted during the year 2010 to evaluate the effect of the treatment with 1-methylcyclopropene (1-MCP) on the ripening process of sapodilla fruits, after refrigeration. The fruits were exposed to 0 and 1 &micro;L/L of 1-MCP for 24 h in airtight chambers at 25&deg;C, after which they were stored at 16&deg;C for four periods of refrigeration (0, 11, 18 and 25 days). At the end of each refrigeration period, the samples were allowed to ripe at 25&deg;C. The results demonstrated the effectiveness of 1-MCP in significantly delaying (P&le;0.05) the ripening process of sapodilla fruits and extending the post-harvest life to 28 days. It was possible to observe a reduction and delay in the climacteric maximums of ethylene and respiration, and a delay in the maximum activity of the pectin methyl esterase enzyme (PME), while weight loss was also reduced. In general, the quality characteristics of ripe fruits were maintained, except for a significant increase in the total soluble solids content of the fruits treated. These results indicate that the treatment with 1-MCP, combined with refrigeration, is an adequate alternative for increasing the shelf life of sapodilla with the aim of facilitating its commercialization. Key words: Sapodilla, 1-methylcyclopropene, ripening, post-harvest, shelf life, refrigeration.

Extruded polymer films for optimal enzyme-catalyzed oxygen scavenging

The use of enzymes as oxygen scavengers has a great potential in the food packaging industry. Enzymes can be incorporated into a coating layer that can be applied directly onto the packaging material. For the system to be fully functional, there is however a need for the packaging to have some barrier properties, to be sealable through heat, and to ensure low or no migration of the active coating to the food. Various combinations of polypropylene (PP), poly(lactic acid) (PLA) and low density polyethylene (LDPE) were extruded onto board coated with the oxygen-scavenging enzyme. Properties such as oxygen-transmission rate, water-vapor transmission rate, heat-sealability, migration and oxygen scavenging capacity were evaluated. All combinations of extruded material resulted in a packaging material able to scavenge the oxygen at both 84% and 100% relative humidity. The greatest decrease in oxygen concentration of the head space of air-tight chambers was achieved with the material extruded with PLA on at least one side. It was found that the extruded plastic is necessary in order to meet the EU directives on migration from food packaging materials of not more than a total of 10mg/dm2 material. All plastics were heat sealable against themselves but not against any of the other plastics and only LDPE adhered strongly to the enzyme-containing coating.

A unified model for VOCs emission/sorption from/on building materials with and without ventilation

An integrated model capable of predicting the emission/sorption of VOCs from/on building materials under the variable air exchange rate has been developed. The semi-analytical solution is presented by using generalized integral transform technique (GITT). The present semi-analytical solution can apply to the cases of ventilation and no ventilation without modification to the coefficients of the semi-analytical solution based on N=0 or not. A self-adaption to N=0 can be realized automatically. Four typical physical processes were adopted to validate the present model: VOCs emission/sorption in ventilated chamber and VOCs emission/sorption in airtight chamber. Good agreements between the computed concentration and the experimental data are obtained. The effect of variable air exchange rate on the concentration in the air is studied in detail. The present model can be used to predict the concentration under the variable air exchange rate.

Microbial Anaerobic Digestion (Bio-Digesters) as an Approach to the Decontamination of Animal Wastes in Pollution Control and the Generation of Renewable Energy

With an ever increasing population rate; a vast array of biomass wastes rich in organic and inorganic nutrients as well as pathogenic microorganisms will result from the diversified human, industrial and agricultural activities. Anaerobic digestion is applauded as one of the best ways to properly handle and manage these wastes. Animal wastes have been recognized as suitable substrates for anaerobic digestion process, a natural biological process in which complex organic materials are broken down into simpler molecules in the absence of oxygen by the concerted activities of four sets of metabolically linked microorganisms. This process occurs in an airtight chamber (biodigester) via four stages represented by hydrolytic, acidogenic, acetogenic and methanogenic microorganisms. The microbial population and structure can be identified by the combined use of culture-based, microscopic and molecular techniques. Overall, the process is affected by bio-digester design, operational factors and manure characteristics. The purpose of anaerobic digestion is the production of a renewable energy source (biogas) and an odor free nutrient-rich fertilizer. Conversely, if animal wastes are accidentally found in the environment, it can cause a drastic chain of environmental and public health complications.

Acceleration of Denitrification in Turbid Rivers Due to Denitrification Occurring on Suspended Sediment in Oxic Waters

High suspended sediment (SPS) concentration exists in many rivers of the world. In the present study, the effects of SPS concentration on denitrification were investigated in airtight chambers with sediment samples collected from the Yellow River which is the largest turbid river in the world. Results from the nitrogen stable ((15)N) isotopic tracer experiments showed that denitrification could occur on SPS in oxic waters and the denitrification rate increased with SPS concentration; this was probably caused by the presence of low-oxygen microsites in SPS. For the water systems with both bed-sediment and SPS, the denitrification kinetics fit well to Logistic model, and the denitrification rate constant increased linearly with SPS concentration (p < 0.01). The denitrification caused by the presence of SPS accounted for 22%, 38%, 53%, and 67% of the total denitrification in systems with 2.5, 8, 15, and 20 g L(-1) SPS, respectively. The activity of denitrifying bacteria in SPS was approximately twice that in bed-sediment, and the denitrifying bacteria population showed an increasing trend with SPS concentration in both SPS and bed-sediment, leading to the increase of denitrification rate with SPS concentration. Furthermore, the denitrification in bed-sediment was accelerated by increased diffusion of nitrate from overlying water to bed-sediment under agitation conditions, which accompanied with the presence of SPS. When with 8 g L(-1) SPS, approximately 66% of the increased denitrification compared to that without SPS was attributed to denitrification on SPS and 34% to agitation conditions. This is the first report of the occurrence of denitrification on SPS in oxic waters. The results suggest that SPS plays an important role in denitrification in turbid rivers; its effect on nitrogen cycle should be considered in future study.

Effects of sevoflurane postconditioning on cell death, inflammation and TLR expression in human endothelial cells exposed to LPS

BackgroundSevoflurane is an anesthetic agent which also participates in protective mechanisms in sepsis, likely due to anti-inflammatory properties. A key tissue in sepsis is the endothelium, which expresses TLR2 and TLR4 receptors, known regulators of inflammatory mechanisms and potential therapeutic targets for this pathology. In this context, we explored the effect of sevoflurane postconditioning in an in vitro sepsis model.MethodsPrimary cultures of human umbilical vein endothelial cells were used for two different experiments. In the first set, cultures were placed in an airtight incubation chamber and exposed to different concentrations of sevoflurane (0,1,3 or 7% vol,) for 1 hour. In the second set, lipopolysaccharide from Escherichia coli 0111:B4 (1 μg/mL) was added to culture medium for 3 hours and cells were subsequently exposed to sevoflurane (0,1,3 or 7% vol,) for 1 hour as explained before. In both cases, cell viability was measured by MTT and Trypan blue assays, TLR2 and TLR4 expression were analyzed by flow cytometry, and TNFα and IL-6 levels were quantified in cell culture media by an immunoassay immediately after exposure, at 6 and 24 hours.ResultsExposure to 3% sevoflurane decreased TLR2 at 24 hours and TLR4 at 6 and 24 hours (both p<0.05), whereas exposure to 7% decreased TLR4 expression at 6 hours (p<0.05). Both 3 and 7% sevoflurane decreased TNF-α and IL-6 levels at 24 hours (both p<0.05). In LPS-stimulated cultures, exposure to 3% sevoflurane was cytoprotective at 6 and 24 hours (p<0.05) compared with control, and decreased TLR2 and TLR4 expression at 24 hours (p<0.05); whereas 7% decreased TLR4 expression at 24 hours (p<0.05). Both 3% and 7% sevoflurane decreased TNF-α and IL-6 levels at 24 hours (both p<0.05).ConclusionsPostconditioning with the halogenated anesthetic agent sevoflurane after LPS stimulation shows a cytoprotective effect in an in vitro model, decreasing cell death and reducing TLR2 and TLR4 expression as well as levels of the inflammatory mediators TNF-α and IL-6 in human endothelial cells.

TLR4 signaling is involved in the protective effect of propofol in BV2 microglia against OGD/reoxygenation

Propofol exhibits neuroprotective effects against hypoxic-ischemic brain injury, but the underlying mechanisms are still not clear. Toll-like receptor 4 (TLR4) plays a considerable role in the induction of innate immune and inflammatory responses. The purposes of this study are to investigate the effect of propofol on the oxygen and glucose deprivation (OGD)/reoxygenation (OGD/R) BV2 microglia and to explore the role of TLR4/myeloid differentiation protein 88 (MyD88)/nuclear factor-kappa B (NF-κB) pathway in the neuroprotective effects of propofol. BV2 microglia were placed into an airtight chamber and in glucose-free medium for OGD/reoxygenation. Cell viability was determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazoliumbromide assay. TLR4 and its downstream signaling molecules, MyD88 and NF-κB expressions were detected by Western blotting. Level of tumor necrosis factor alpha (TNF-α) in culture medium was determined with enzyme-linked immunosorbent assay. BV2 microglia apoptosis was determined by flow cytometry. We found that pretreatment with propofol significantly alleviated the hypoxic injury in BV2 microglia. Propofol inhibited upregulation of TLR4, MyD88, and NF-κB expressions in BV2 microglia exposed to OGD/reoxygenation. Propofol pretreatment also significantly reduced the production of TNF-α and apoptosis in OGD/reoxygenation BV2 microglia. The results indicated that TLR4 and its downstream MyD88-dependent signaling pathway contributed to neuroprotection of propofol to microglia exposed to OGD/reoxygenation.

226Ra measurements through gamma spectrometric counting of radon progenies: How significant is the loss of radon?

Most determinations of 226Ra are based on gamma spectrometric measurements of 226Ra progenies 214Pb and 214Bi. This approach assumes radioactive equilibrium between these radionuclides which is normally achieved by sealing the sample containers so that the direct decay product of 226Ra, 222Rn, is not lost. We investigated to what extent 222Rn is lost from various sample containers usually used for gamma spectrometric measurements and which have been sealed applying different techniques. The sample containers containing reference material with known amounts of 226Ra were placed in an air-tight measurement chamber and we measured the 222Rn accumulation over time in the chamber. Taking the leakage of the experimental set-up into account, we related the measured 222Rn to the 226Ra content of the reference material to calculate the 222Rn loss from the sample containers. For most of the reference materials investigated the sealing techniques applied reduced the 222Rn loss to <6%. We found that BaSO4 sample matrix and plastic containers sealed with epoxy resin most effectively minimize the 222Rn loss (<1%). For those sample matrixes like phosphogypsum and Mn-fibers, which are characterized by high emanation and diffusion of radon, sealing is very important to reduce the 222Rn loss.