Localisation of allergens in ryegrass pollen and in airborne micronic particles

In Melbourne, Australia, grass pollen allergens, especially from ryegrass, are a major cause of allergic hayfever and asthma. This review outlines recent developments in our understanding of how grass pollen allergens find their way into the atmosphere and how they are transported in particulate form. Much of this work has relied on antibody technology in immunological and immunocytochemical investigations. The localisation of allergens in situ has proved difficult due to their water-soluble character. Recently, allergens have been localised in developing ryegrass pollen by dryfixation, rapid-freeze and freeze-substitution techniques. This involved anthers being substituted in a mixture of aldehydes, organic solvents, and 2,2-dimethoxypropane. Incubation in dimethylsulfoxide prior to embedding in LR Gold resin provided good infiltration with freeze-substituted material. Immunogold-labelled sections show that the major allergens, Lol p 1 and Lol p 5, are synthesised in the pollen cytoplasm from the early bicellular stage, soon after the first starch granules are formed. From the early tricellular stage, Lol p 5 moves into the starch granules where it remains until maturity. Lol p 1 is localised in the cytoplasm of mature pollen grains. The incidence of airborne grass pollen, as measured in pollen traps, correlates with hayfever symptoms. Forecasting models which rely on rainfall and temperature data have been produced for the grass pollen (daily and seasonal) counts in Melbourne. Research over the past six years has shed light on the causes of grass-pollen-induced asthma. Micronic particles in the atmosphere may be starch granules originating from pollen grains osmotically ruptured by rainwater. Ultrastructural and immunological characterisation of micronic particles collected from outdoor air filters confirm the presence of airborne starch granules. These are loaded with grass pollen allergens, occur in the atmosphere especially after rainfall, and correlate significantly with instances of allergic asthma. Diesel particles might also play a role in the transmission of grass pollen allergens and thus become an extra asthma trigger. A variation in the mode of release of micronic particles occurs in other species, such as birch, where such particles are derived from burst birch pollen tubes. These particles are positive for Bet v 1 and are starch granules which are released into the atmosphere after light rain as a result of pollen germination on, e.g., leaves. After subsequent rupture of pollen tubes their contents are released when conditions become drier.

Source of Bet v 1 loaded inhalable particles from birch revealed

Allergenic proteins present in pollen grains, when inhaled, interact with the airways to cause an attack of asthma in susceptible humans. In one system, grass pollen grains rupture osmotically in rainfall, releasing allergen-containing inhalable particles into the atmosphere. In contrast, birch tree pollen grains do not rupture under these conditions, yet the major allergen, Bet v 1, has been detected in the atmosphere in inhalable particles of unknown origin. It is possible that Bet v 1 may diffuse from intact settled pollen grains and the allergenic material may again become airborne, interacting with settled fine particles from other sources prior to resuspension. This study investigates the mechanism for the release of birch pollen allergen-containing inhalable particles from pollen grains. We propose the hypothesis that (1) airborne birch pollen grains settle on nearby leaf surfaces; (2) then, following light rainfall, the grains germinate and, (3) later, pollen tubes burst, releasing inhalable particles carrying Bet v 1 into the atmospheric aerosol.   We used microscopic analyses of pollen behaviour following anther opening, a Burkard volumetric trap for pollen counts and a high volume air sampler with a two-stage cascade impactor for quantitative immunochemical analyses of Bet v 1. On dry days of high birch pollen count (48 grains/m3, 1.5 ng/m3 of Bet v 1), we found that the surfaces of birch leaves became coated with pollen. This ”pollen rain” is a source of secondary emission of allergens into the atmosphere. We observed that following light rainfall (<1 mm per day), about 80% of the birch pollen grains germinated, producing pollen tubes, especially in the sticky surface secretions of leaf glands. These pollen tubes may grow up to 300 μm in length prior to rupturing, each releasing about 400 starch granules coated with allergen molecules that may, after drying, be dispersed into the aerosol. On these days following light rainfall, the highest atmospheric levels of Bet v 1 (1.18 ng/m3) are associated with inhalable particles. Following heavy rainfall, both pollen and inhalable particles are washed from the atmosphere. Immunoprinting studies show that Bet v 1 is associated with starch granules rather than the smaller orbicules. Bet v 1 is present in the atmosphere in large particles, i.e. in particular pollen grains and in inhalable particles, i.e. in particular starch granules.

Meteorological influences on respirable fragment release from Chinese elm pollen

Exposure to airborne pollen from certain plants can cause allergic disease, leading to acute respiratory symptoms. Whole pollen grains, 15–90 μ m-sized particles, provoke the upper respiratory symptoms of rhinitis (hay fever), while smaller pollen fragments capable of depositing in the lower respiratory tract have been proposed as the trigger for asthma. In order to understand factors leading to pollen release and fragmentation we have examined the rupture of Chinese elm pollen under controlled laboratory conditions and in the outdoor atmosphere. Within 30 minutes after immersion in water, 70% of fresh Chinese pollen ruptures, rapidly expelling cytoplasm. Chinese elm flowers, placed in a controlled atmosphere chamber, emitted pollen and pollen debris after a sequential treatment of 98% relative humidity followed by drying and a gentle disturbance. Immunologic assays of antigenic proteins specific to elm pollens revealed that fine particulate material (D p < 2 μ m) collected from the chamber contained elm pollen antigens. In a temporal study of the outdoor urban atmosphere during the Chinese elm bloom season of 2004, peak concentrations of pollen and fine pollen fragments occurred at the beginning of the season when nocturnal relative humidity (RH) exceeded 90%. Following later periods of hot dry weather, pollen counts decreased to zero. The Chinese elm pollen fragments also decreased during the hot weather, but later displayed additional peaks following periods of more moderate RH and temperature, indicating that pollen counts underestimate total atmospheric pollen allergen concentrations. Pollen fragments thus increase the biogenic load in the atmosphere in a form that is no longer recognizable as pollen and, therefore, is not amenable to microscopic analysis. This raises the possibility of exposure of sensitive individuals to pollen allergens in the form of fine particles that can penetrate into the lower airways and pose potentially severe health risks.

The interrelationship between the accumulation of lipids, protein and the level of acyl carrier protein during the development of Brassica napus L. pollen

Lipid accumulation during pollen and tapetal development was studied using cryostat sections of unfixed anthers from Brassica napus (rapeseed). Diamidino-2-henylindole (DAPI), a DNA fluorochrome, was used to stain the pollen nuclei in order to identify ten stages of pollen development in Brassica. Storage lipids (i.e. triacylglycerides) were stained using the fluorochrome Nile red. Pollen coat lipids are formed in tapetal plastids between the mid-vacuolate and early maturation pollen stages. The pollen coat components, including lipids and a proportion of the proteins, are derived from the remnants of the tapetum, after its rupture, during the second pollen mitosis. Quantitative microfluorometric analyses demonstrated four phases of lipid body accumulation or depletion in the developing pollen cytoplasm. The majority of storage lipids found in the cytoplasm of the mature pollen grain accumulated during the late vacuolate and early maturation stages when the pollen is bicellular. The level of acyl carrier protein, a protein integrally involved in lipid synthesis, was also found to be maximal in the developing pollen during the bicellular pollen stages of development. This coincided with the most active period of lipid accumulation. These data could indicate that the lipids of the pollen are synthesized in situ, by metabolic processes regulated by expression of genes in the haploid genome.

Double layer structure of ionic liquids at the Au(111) electrode interface : an atomic force microscopy investigation

The double layer structure of two ionic liquids (ILs), 1-butyl-1- methylpyrrolidinium tris(pentafluoroethyl)trifluorophosphate ([Py ₁,₄]FAP) and 1-ethyl-3-methylimidazolium tris(pentafluoroethyl) trifluorophosphate ([EMIm]FAP) at the polarized Au(111) electrode interface is probed using Atomic Force Microscopy force measurements. The force-separation profiles suggest a multilayered morphology is present at the electrified Au(111)-IL interface, with more near surface layers detected at higher potentials. At the (slightly negative) open circuit potential, multiple ion layers are present, and the innermost layer, in contact with the Au(111) surface, is enriched in the cation due to electrostatic adsorption. Upon applying negative electrode potentials (-1.0 V, -2.0 V), stronger IL near surface structure is detected: both the number of ion layers and the force required to rupture these layers increases. Positive electrode potentials (+1.0 V, +2.0 V) also enhance IL near surface structure, but not as much as negative potentials, because surface-adsorbed anions are less effective at templating structure in subsequent layers than cations. This interfacial structure is not consistent with a double layer in the Stern-Gouy-Chapman sense, as there is no diffuse layer. The structure is consistent with a capicitative double-layer model, with a very small separation distance between the planes of charge.

Hog dreaming

Hog dreaming is representative of the 'notion of rupture/rapture and the contradictory thought that the space we represent ourselves and others in do not always designate the human in us; they can also triangulate and expose that secret and hidden part of us that is animal.'

The drainage of thin liquid films between solid surfaces

We present measurements of the thickness as a function of time of liquid films as they are squeezed between molecularly smooth mica surfaces. Three Newtonian, nonpolar liquids have been studied: octamethylcyclotetrasiloxane, n-tetradecane, and n-hexadecane. The film thicknesses are determined with an accuracy of 0.2 nm as they drain from ∼1 μm to a few molecular layers. Results are in excellent agreement with the Reynolds theory of lubrication for film thicknesses above 50 nm. For thinner films the drainage is slower than the theoretical prediction, which can be accounted for by assuming that the liquid within about two molecular layers of each solid surface does not undergo shear. In very thin films the continuum Reynolds theory breaks down, as drainage occurs in a series of abrupt steps whose size matches the thickness of molecular layers in the liquid. The presence of trace amounts of water has a dramatic effect on the drainage of a nonpolar liquid between hydrophilic surfaces, causing film rupture which is not observed in the dry liquids.

Hybrid perspectives : defining the relativity of culture and identity through migration experiences

This paper examines how culture and identity can be relatively defined through hybrid perspectives in relation to migration experiences. Addressing and portraying definitions of culture and identity is crucial in understanding how notions of such issues connect and initiate the migrant subject through new experiences, perspectives and ways of being. In enunciating the transitions from home to a new place, and elaborating on the rupture of an inherited culture and grounded identity, I refer to them through self-reflexive perspectives. The search for meaning through appraisals of cultural lineage and linguistic capital through a Diaspora, a post colonial history and lived life experiences from my home country, pre-empts the ambivalent and hybrid status in defining culture(s) and identit(ies). It is crucial to recognise how challenges for adaptation to new culture, language, societal norms, and differences in class, nationality, race and gender play specific roles in the migrant experience. My current experiences of migration to Australia are narrations of encountered difficulties, fears, inhibitions, new aspirations, perceptions and perspectives, which map an ‘identity crisis.’ From this narrative structure, I investigate through my ongoing PhD study, how my artistic expression and representations progress towards experiences, and themes that metaphorically reflect, inspire and enact the hybrid structures of culture(s) and identit(ies). Explored reflexively my representations suggest how the ‘liminal space’ or the ‘third space,’ (Bhabha, 1990) express transitions about the ‘self’ and my artistic expression, which enable further reflection and positions to emerge and extend to metaphorical expressions.

Emerging engineered magnetic nanoparticulate probes for molecular MRI of atherosclerosis : how far have we come?

Atherosclerosis is a chronic, progressive, immunoinflammatory disease of the large and medium-sized arteries, and a major cause of cardiovascular diseases. Atherosclerosis often progresses silently for decades until the occurrence of a major catastrophic clinical event such as myocardial infarction, cardiac arrest and stroke. The main challenge in the diagnosis and management of atherosclerosis is to develop a safe, noninvasive technique that is accurate and reproducible, which can detect the biologically active high-risk vulnerable plaques (with ongoing active inflammation, angiogenesis and apoptosis) before the occurrence of an acute clinical event. This Journal Article reviews the events involved in the pathogenesis of atherosclerosis in light of recently advanced understanding of the molecular pathogenesis of the disease. Next, we elaborate on the interesting developments in molecular MRI, by describing the recently engineered magnetic nanoparticulate probes targeting clinically promising molecular and cellular players/processes, involved in early atherosclerotic lesion formation to plaque rupture and erosion.

Strain hardening behavior of high performance FBDP, TRIP and TWIP steels

Based on n-value differential equation and microstructural observation, strain hardening behaviors of FBDP, TRIP, and TWIP steels during uniaxial tension were investigated. TRIP steel exhibits both superior strength and ductility than FBDP steel, and TWIP steel displays much higher total and uniform elongations in comparison to FBDP and TRIP steels. The instantaneous n values of FBDP and TRIP steels increase at small strains, reach a maximum value, smoothly decrease at higher strains, and then rapidly drop up to the specimen rupture. The strain hardening of TRIP steel persists at higher strains where that of FBDP steel begins to diminish. TWIP steel exhibits gradually increased instantaneous n values over the whole uniform plastic deformation, implying that TWIP steel shows a much larger strain hardening capability than FBDP and TRIP steels.

In vitro strain measurements in cerebral aneurysm models for cyber-physical diagnosis

Background: The development of new diagnostic technologies for cerebrovascular diseases requires an understanding of the mechanism behind the growth and rupture of cerebral aneurysms. To provide a comprehensive diagnosis and prognosis of this disease, it is desirable to evaluate wall shear stress, pressure, deformation and strain in the aneurysm region, based on information provided by medical imaging technologies. Methods: In this research, we propose a new cyber-physical system composed of in vitro dynamic strain experimental measurements and computational fluid dynamics (CFD) simulation for the diagnosis of cerebral aneurysms. A CFD simulation and a scaled-up membranous silicone model of a cerebral aneurysm were completed, based on patient-specific data recorded in August 2008. In vitro blood flow simulation was realized with the use of a specialized pump. A vision system was also developed to measure the strain at different regions on the model by way of pulsating blood flow circulating inside the model. Results: Experimental results show that distance and area strain maxima were larger near the aneurysm neck (0.042 and 0.052), followed by the aneurysm dome (0.023 and 0.04) and finally the main blood vessel section (0.01 and 0.014). These results were complemented by a CFD simulation for the addition of wall shear stress, oscillatory shear index and aneurysm formation index. Diagnosis results using imaging obtained in August 2008 are consistent with the monitored aneurysm growth in 2011. Conclusion: The presented study demonstrates a new experimental platform for measuring dynamic strain within cerebral aneurysms. This platform is also complemented by a CFD simulation for advanced diagnosis and prediction of the growth tendency of an aneurysm in endovascular surgery.

Three-dimensional numerical simulation of blood flow in mouse aortic arch around atherosclerotic plaques

Atherosclerosis is a progressive disease, involving the build-up of lipid streaks in artery walls, leading to plaques. Understanding the development of atherosclerosis and plaque vulnerability is critically important since plaque rupture can result in heart attack or stroke. Plaques can be divided into two distinct types: those likely to rupture (vulnerable) or less likely to rupture (stable). In the last decade, researchers have been interested in studying the influence of the mechanical effects (blood shear stress, pressure forces and structural stress) on the plaque formation, progression and rupture processes but no general agreement has been found. The purpose of the present work is to include more realistic conditions for the numerical calculations of the blood flow by implementing real geometries with plaques in the numerical model. Hemodynamical parameters are studied in both diseased and healthy configurations. The healthy configuration is obtained by removing numerically the plaques from three dimensional geometries obtained by micro-computed tomography. A new hemodynamical parameter is also introduced to relate the location of plaques to the characteristics of the flow in the healthy configuration. © 2014 .

Is anterior cruciate reconstruction superior to conservative treatment?

Not all patients who have a rupture of the anterior cruciate ligament (ACL) elect to have surgical reconstruction. The aim of this study was to assess the short-to-medium-term results of patients who chose conservative management in comparison to patients who had reconstructive surgery within the same time period. Sixty-three patients with an ACL injury were retrospectively studied. Forty patients were managed, according to patient choice, with ACL reconstruction and 23 conservatively. Four validated questionnaires were used to assess general and knee-specific function in a cohort with a median age of 32 years and a median follow-up period of 38 months. Patients were matched on demographic variables except for gender. There were no statistically significant differences in the outcome measures, and the majority of patients would proceed with the same treatment in the event the control leg became injured. Patients who elect to have conservative management of an ACL rupture can achieve similar function and satisfaction to those who elect to have reconstruction. Until a large randomized controlled trial is conducted, patients need to be made aware of the merits of both management strategies and the lack of evidence of superiority of one over the other.

Epoxy nanocomposites containing magnetite-carbon nanofibers aligned using a weak magnetic field

Abstract Novel magnetite-carbon nanofiber hybrids (denoted by Fe3O4@CNFs) have been developed by coating carbon nanofibers (CNFs) with magnetite nanoparticles in order to align CNFs in epoxy using a relatively weak magnetic field. Experimental results have shown that a weak magnetic field (∼mT) can align these newly-developed nanofiber hybrids to form a chain-like structure in the epoxy resin. Upon curing, the epoxy nanocomposites containing the aligned Fe3O4@CNFs show (i) greatly improved electrical conductivity in the alignment direction and (ii) significantly higher fracture toughness when the Fe3O4@CNFs are aligned normal to the crack surface, compared to the nanocomposites containing randomly-oriented Fe3O4@CNFs. The mechanisms underpinning the significant improvements in the fracture toughness have been identified, including interfacial debonding, pull-out, crack bridging and rupture of the Fe3O4@CNFs, and plastic void growth in the polymer matrix.

A self-supported, flexible, binder-free pseudo-supercapacitor electrode material with high capacitance and cycling stability from hollow, capsular polypyrrole fibers

Flexible energy devices with high performance and long-term stability are highly promising for applications in portable electronics, but remain challenging to develop. As an electrode material for pseudo-supercapacitors, conducting polymers typically show higher energy storage ability over carbon materials and larger conductivity than transition-metal oxides. However, conducting polymer-based supercapacitors often have poor cycling stability, attributable to the structural rupture caused by the large volume contrast between doping and de-doping states, which has been the main obstacle to their practical applications. Herein, we report a simple method to prepare a flexible, binder-free, self-supported polypyrrole (PPy) supercapacitor electrode with high cycling stability through using novel, hollow PPy nanofibers with porous capsular walls as a film-forming material. The unique fiber structure and capsular walls provide the PPy film with enough free-space to adapt to volume variation during doping/de-doping, leading to super-high cycling stability (capacitance retention > 90% after 11000 charge-discharge cycles at a high current density of 10 A g^-1) and high rate capability (capacitance retention ∼ 82.1% at a current density in the range of 0.25-10 A g^-1).