Metagenomic Human Repiratory Air in a Hospital Environment

Hospital-acquired infection (HAI) or nosocomial infection is an issue that frequent hospital environment. We believe conventional regulated Petri dish method is insufficient to evaluate HAI. To address this problem, metagenomic sequencing was applied to screen airborne microbes in four rooms of Beijing Hospital. With air-in amount of sampler being setup to one person’s respiration quantity, metagenomic sequencing identified huge numbers of species in the rooms which had already qualified widely accepted petridish exposing standard, imposing urgency for new technology. Meanwhile,the comparative culture only got small portion of recovered species and remain blind for even cultivable pathogens reminded us the limitations of old technologies. To the best of our knowledge, the method demonstrated in this study could be broadly applied in hospital indoor environment for various monitoring activities as well as HAI study. It is also potential as a transmissible pathogen real-time modelling system worldwide.     

Evaluation of a New Environmental Sampling Protocol for Detection of Human Norovirus on Inanimate Surfaces

Inanimate surfaces are regarded as key vehicles for the spread of human norovirus during outbreaks. ISO method 15216 involves the use of cotton swabs for environmental sampling from food surfaces and fomites for the detection of norovirus genogroup I (GI) and GII. We evaluated the effects of the virus drying time (1, 8, 24, or 48 h), swab material (cotton, polyester, rayon, macrofoam, or an antistatic wipe), surface (stainless steel or a toilet seat), and area of the swabbed surface (25.8 cm² to 645.0 cm²) on the recovery of human norovirus. Macrofoam swabs produced the highest rate of recovery of norovirus from surfaces as large as 645 cm². The rates of recovery ranged from 2.2 to 36.0% for virus seeded on stainless-steel coupons (645.0 cm²) to 1.2 to 33.6% for toilet seat surfaces (700 cm²), with detection limits of 3.5 log₁₀ and 4.0 log₁₀ RNA copies. We used macrofoam swabs to collect environmental samples from several case cabins and common areas of a cruise ship where passengers had reported viral gastroenteritis symptoms. Seventeen (18.5%) of 92 samples tested positive for norovirus GII, and 4 samples could be sequenced and had identical GII.1 sequences. The viral loads of the swab samples from the cabins of the sick passengers ranged from 80 to 31,217 RNA copies, compared with 16 to 113 RNA copies for swab samples from public spaces. In conclusion, our swab protocol for norovirus may be a useful tool for outbreak investigations when no clinical samples are available to confirm the etiology.     

Effect of Air Plasma Processing on the Adsorption Behaviour of Bovine Serum Albumin on Spin-Coated PMMA Surfaces

This paper reports the adsorption of Bovine Serum Albumin （BSA） onto Dielectric Barrier Discharge （DBD） processed Poly（methyl methacrylate） （PMMA） surfaces by a Quartz Crystal Microbalance with Dissipation monitoring （QCM-D） technique. The purpose is to study the influence of DBD processing on the nature and scale of BSA adsorption on PMMA surface in vitro. It was observed that DBD processing improves the surface wettability of PMMA film, a fact attributable to the changes in surface chemistry and topography. Exposure of the PMMA to Phosphate Buffed Saline （PBS） solution in the QCM-D system resulted in surface adsorption which reaches an equilibrium after about 30 minutes for pristine PMMA, and 90 minutes for processed PMMA surface. Subsequent injection of BSA in PBS indicated that the protein is immediately adsorbed onto the PMMA surface. It was revealed that adsorption behaviour of BSA on pristine PMMA differs from that on processed PMMA surface. A slower adsorption kinetics was observed for pristine PMMA surface, whilst a quick adsorption kinetics for processed PMMA. Moreover, the dissipation shift of protein adsorption suggested that BSA forms a more rigid structure on pristine PMMA surface that on processed surface. These data suggest that changes in wettability and attendant chemical properties and surface texture of the PMMA surface may play a significant role in BSA adsorption process.     

Epidermal Growth Factor Receptor Activation Remodels the Plasma Membrane Lipid Environment To Induce Nanocluster Formation

Signal transduction is regulated by the lateral segregation of proteins into nanodomains on the plasma membrane. However, the molecular mechanisms that regulate the lateral segregation of cell surface receptors, such as receptor tyrosine kinases, upon ligand binding are unresolved. Here we used high-resolution spatial mapping to investigate the plasma membrane nanoscale organization of the epidermal growth factor (EGF) receptor (EGFR). Our data demonstrate that in serum-starved cells, the EGFR exists in preformed, cholesterol-dependent, actin-independent nanoclusters. Following stimulation with EGF, the number and size of EGFR nanoclusters increase in a time-dependent manner. Our data show that the formation of EGFR nanoclusters requires receptor tyrosine kinase activity. Critically, we show for the first time that production of phosphatidic acid by phospholipase D2 (PLD2) is essential for ligand-induced EGFR nanocluster formation. In accordance with its crucial role in regulating EGFR nanocluster formation, we demonstrate that modulating PLD2 activity tunes the degree of EGFR nanocluster formation and mitogen-activated protein kinase signal output. Together, these data show that EGFR activation drives the formation of signaling domains by regulating the production of critical second-messenger lipids and modifying the local membrane lipid environment.The epidermal growth factor (EGF) receptor (EGFR) is a single transmembrane domain protein that possesses intrinsic tyrosine kinase (TK) activity. Ligand binding to the extracellular domain induces conformational changes that promote activation of the intracellular TK domain. The kinase domain then autophosphorylates a number of tyrosine residues in the C-terminal region of the protein, creating docking sites for adapter and effector proteins. Thus, the active form of the EGFR could reasonably be expected to be a dimer. However, recent studies using single-molecule imaging, image correlation spectroscopy (ICS), fluorescence correlation spectroscopy (FCS), and immunoelectron microscopy (immuno-EM) show that the EGFR is, in fact, nonrandomly organized into oligomers on the plasma membrane (6, 7, 16, 34, 44). ICS measurements estimate that, in the absence of ligand, there are, on average, 2.2 EGFRs per cluster, which increases to 3.7 receptors per cluster upon stimulation (7). Single-molecule tracking experiments also suggest that unliganded EGFRs continually fluctuate between monomers and dimers that are primed for activation (5). Furthermore, the organization of the EGFR is dynamic and clustering of the EGFR increases over time after EGF stimulation (7, 16). However, neither the precise role of EGFR oligomerization in signal transduction nor the mechanisms driving oligomer formation have been resolved.The organization of the EGFR into oligomers is dependent upon cellular cholesterol. Saffarian et al., using FCS, estimated that 70% of EGFRs exist as monomers, 20% as dimers, and 10% as oligomers (34). However, depletion of cholesterol decreases the percentage of monomeric receptors and increases the proportion of oligomeric receptors. Cholesterol depletion and actin depolymerization also alter the diffusion coefficient of the EGFR and the confinement area size (22). The finding that EGFR membrane organization is dependent upon cholesterol is of particular interest because a number of studies have demonstrated that EGFR activity is negatively regulated by cholesterol (4, 23, 28, 32).Phospholipase D2 (PLD2) hydrolyzes phosphatidylcholine (PC) to produce choline and phosphatidic acid (PA). PLD2 is localized to the plasma membrane (10), associates with the EGFR (39), and is rapidly activated upon EGF stimulation, leading to increased production of PA (15, 38, 39). A number of lines of evidence suggest that PA is an important mediator of EGFR action. First, exogenous PA is mitogenic when incubated with cells (17, 19, 42, 45). Second, direct interaction with membrane PA regulates the activity of a number of components downstream of the EGFR, including Sos (47) and Raf (12, 13, 30, 31).In the current study, we used high-resolution spatial analysis techniques to investigate EGFR plasma membrane organization. Using these approaches, we identified PA as the key molecular component responsible for driving EGFR nanocluster formation in response to EGF binding and demonstrated that the level of PLD2 activity regulates the duration of mitogen-activated protein kinase (MAPK) signal output.     

Aerococcus viridans in the Hospital Environment

Aerococcus viridans has been described as an airborne organism prevalent in occupied rooms. It has also been described as an organism having many characteristics that might cause it to be confused with streptococci or staphylococci, and this may account for the fact that the presence of A. viridans has not been reported in the hospital environment or in clinical specimens. Swab specimens were taken from 47 objects in 11 different areas in a local hospital, cultured overnight in Trypticase Soy Broth, and streaked on blood-agar and on a selective serum agar containing potassium tellurite and crystal violet. Of 85 alpha-hemolytic cultures isolated, 11 proved to be typical A. viridans based on diagnostic tests that also were applied to a collection of gram-positive cocci, including authentic strains of A. viridans. These organisms are gram-positive cocci with a strong tendency toward tetrad formation in broth cultures. They are predominantly aerobic, have a very weak catalase activity, and lack porphyrin respiratory enzymes. Three similar cultures also were obtained from routine clinical specimens.     

Contribution of Spores to the Ability of Clostridium difficile To Adhere to Surfaces

Clostridium difficile is the commonest cause of hospital-acquired infection in the United Kingdom. We characterized the abilities of 21 clinical isolates to form spores; to adhere to inorganic and organic surfaces, including stainless steel and human adenocarcinoma cells; and to germinate. The composition of culture media had a significant effect on spore formation, as significantly more spores were produced in brain heart infusion broth (Student''s t test; P = 0.018). The spore surface relative hydrophobicity (RH) varied markedly (14 to 77%) and was correlated with the ability to adhere to stainless steel. We observed no correlation between the ribotype and the ability to adhere to steel. When the binding of hydrophobic (DS1813; ribotype 027; RH, 77%) and hydrophilic (DS1748; ribotype 002; RH, 14%) spores to human gut epithelial cells at different stages of cell development was examined, DS1813 spores adhered more strongly, suggesting the presence of surface properties that aid attachment to human cells. Electron microscopy studies revealed the presence of an exosporium surrounding DS1813 spores that was absent from spores of DS1748. Finally, the ability of spores to germinate was found to be strain and medium dependent. While the significance of these findings to the disease process has yet to be determined, this study has highlighted the importance of analyzing multiple isolates when attempting to characterize the behavior of a bacterial species.     

Cold Plasma: an Alternative Technology for the Starch Modification

Cold plasma is an emerging novel non-thermal technology in the sector of food processing. In the present review we will discuss the recent scientific reports on properties of cold plasma treated starches. For industrial use native starch is subject to modification to enhance the properties. This paper reviews on the mechanism of starch modification by plasma reactive species, briefly discussing its effects on properties. The effect of cold plasma on starches depends on the type of feed gas, voltage applied and treatment time. The alteration in the properties is mainly due to depolymerization and cross linking of amylose and amylopectin side chains. After plasma treatment there is decrease in molecular weight, viscosity, and gelatinization temperatures. Plasma etching increased the surface energy and enhanced the hydrophilicity of the starch granules. We can conclude that cold plasma is as alternative technology to modify the properties of starch.     

Estimation of the Microcirculatory Response to the Effect of Cold Helium Plasma

Biophysics - Abstract—This study was aimed at estimating the microcirculatory response to local application of cold helium plasma. Experiments were performed with 20 healthy male Wistar rats,...     

Investigation of Elements Sufficient To Imprint the Mouse Air Promoter

Imprinted maternal-allele-specific expression of the mouse insulin-like growth-factor type 2 receptor (Igf2r) gene depends on a 3.7-kb element named region 2, located in the second intron of the gene. Region 2 carries a maternal-allele-specific methylation imprint and contains an imprinted CpG island promoter (Air) that expresses a noncoding antisense RNA from the paternal inherited allele only. Here, we use transgenes to test the minimal requirements for imprinting of Air and to test if the action of region 2 is restricted to Igf2r. Transgenes up to 9 kb with Air as a single promoter are expressed but not imprinted. When coupled to the Igf2r CpG island promoter on a 44-kb transgene, Air was imprinted in one of three lines. However, Air on a 4.6-kb fragment is also imprinted in 2 of 14 lines when inserted in an intron of an adenine phosphoribosyltransferase (Aprt) transgene, and in one line, the imprinted methylation and expression of Air have been transferred onto the Aprt CpG island promoter. These data suggest that a dual CpG island promoter setting may facilitate Air imprinting as a short transgene and also show that Air can transfer imprinting onto other genes. However, for reliable Air imprinting, elements are necessary that are located outside a 44-kb region spanning the Air-Igf2r promoters.     

Effects of Acid Adaptation of Escherichia coli O157:H7 on Efficacy of Acetic Acid Spray Washes To Decontaminate Beef Carcass Tissue

Exposure to low pH and organic acids in the bovine gastrointestinal tract may result in the induced acid resistance of Escherichia coli O157:H7 and other pathogens that may subsequently contaminate beef carcasses. The effect of acid adaptation of E. coli O157:H7 on the ability of acetic acid spray washing to reduce populations of this organism on beef carcass tissue was examined. Stationary-phase acid resistance and the ability to induce acid tolerance were determined for a collection of E. coli O157:H7 strains by testing the survival of acid-adapted and unadapted cells in HCl-acidified tryptic soy broth (pH 2.5). Three E. coli O157:H7 strains that were categorized as acid resistant (ATCC 43895) or acid sensitive (ATCC 43890) or that demonstrated inducible acid tolerance (ATCC 43889) were used in spray wash studies. Prerigor beef carcass surface tissue was inoculated with bovine feces containing either acid-adapted or unadapted E. coli O157:H7. The beef tissue was subjected to spray washing treatments with water or 2% acetic acid or left untreated. For strains ATCC 43895 and 43889, larger populations of acid-adapted cells than of unadapted cells remained on beef tissue following 2% acetic acid treatments and these differences remained throughout 14 days of 4°C storage. For both strains, numbers of acid-adapted cells remaining on tissue following 2% acetic acid treatments were similar to numbers of both acid-adapted and unadapted cells remaining on tissue following water treatments. For strain ATCC 43890, there was no difference between populations of acid-adapted and unadapted cells remaining on beef tissue immediately following 2% acetic acid treatments. These data indicate that adaptation to acidic conditions by E. coli O157:H7 can negatively influence the effectiveness of 2% acetic acid spray washing in reducing the numbers of this organism on carcasses.     

The Origin of Life in the Context of Inanimate Nature

Biophysics - Questions about the nature of life and the ability of living things to evolve are still attracting attention of scientists from different backgrounds. The idea that all living...     

Differential Effects of Cold Atmospheric Plasma in the Treatment of Malignant Glioma

Objective

Cold atmospheric plasma (CAP) has recently been shown to selectively target cancer cells with minimal effects on normal cells. We systematically assessed the effects of CAP in the treatment of glioblastoma.

Methods

Three glioma cell lines, normal astrocytes, and endothelial cell lines were treated with CAP. The effects of CAP were then characterized for viability, cytotoxicity/apoptosis, and cell cycle effects. Statistical significance was determined with student''s t-test.

Results

CAP treatment decreases viability of glioma cells in a dose dependent manner, with the ID50 between 90-120 seconds for all glioma cell lines. Treatment with CAP for more than 120 seconds resulted in viability less than 35% at 24-hours posttreatment, with a steady decline to less than 20% at 72-hours. In contrast, the effect of CAP on the viability of NHA and HUVEC was minimal, and importantly not significant at 90 to 120 seconds, with up to 85% of the cells remained viable at 72-hours post-treatment. CAP treatment produces both cytotoxic and apoptotic effects with some variability between cell lines. CAP treatment resulted in a G2/M-phase cell cycle pause in all three cell lines.

Conclusions

This preliminary study determined a multi-focal effect of CAP on glioma cells in vitro, which was not observed in the non-tumor cell lines. The decreased viability depended on the treatment duration and cell line, but overall was explained by the induction of cytotoxicity, apoptosis, and G2/M pause. Future studies will aim at further characterization with more complex pre-clinical models.     

Forming of the Gaseous Environment by Insects in the Intergranular Air

Entomological Review - It is experimentally shown that intergranular air in the wheat stock infested by insect pests has a substantially higher concentration of carbon dioxide with significantly...     

Equations of Plasma Equilibrium in a Magnetic Field with Three-Dimensional Magnetic Surfaces

Plasma Physics Reports - A system of equations that describe the static equilibrium of plasma in a magnetic field with three-dimensional magnetic surfaces of toroidal topology is obtained. The...     

Mathematical Estimation of the Level of Microbial Contamination on Spacecraft Surfaces by Volumetric Air Sampling

Microbiological sampling methods presently used for enumeration of microorganisms on spacecraft surfaces require contact with easily damaged components. Estimation of viable particles on surfaces using air sampling methods in conjunction with a mathematical model would be desirable. Parameters necessary for the mathematical model are the effect of angled surfaces on viable particle collection and the number of viable cells per viable particle. Deposition of viable particles on angled surfaces closely followed a cosine function, and the number of viable cells per viable particle was consistent with a Poisson distribution. Other parameters considered by the mathematical model included deposition rate and fractional removal per unit time. A close nonlinear correlation between volumetric air sampling and airborne fallout on surfaces was established with all fallout data points falling within the 95% confidence limits as determined by the mathematical model.     

Mesophilic Mineral-Weathering Bacteria Inhabit the Critical-Zone of a Perennially Cold Basaltic Environment

The weathering of silicate in the world's critical-zone (rock-soil interface) is a natural mechanism providing a feedback on atmospheric CO₂ concentrations through the carbonate-silicate cycle. We examined culturable bacterial communities from a critical-zone in western Iceland to determine the optimum growth temperature and their ability to solubilize phosphate-containing minerals, which are abundant within the critical-zone area examined here. The majority of isolated bacteria were able to solubilize mineral-state phosphate. Almost all bacterial isolates were mesophilic (growth optima of 20–45°C), despite critical-zone temperatures that were continuously below 15°C, although all isolates could grow at temperatures associated with the critical-zone (?2.8–13.1°C). Only three isolates were shown to have thermal optima for growth that were within temperatures experienced at the critical-zone. These findings show that the bacteria that inhabit the western Icelandic critical-zone have temperature growth optima suboptimally adapted to their environment, implying that other adaptations may be more important for their long-term persistance in this environment. Moreover, our study showed that the cold basaltic critical-zone is a region of active phosphate mineral-weathering.