Staphylococcus aureus leucocidin, a virulence factor in bovine mastitis

The involvement of Staphylococcus aureus exosecretions in bovine udder infection (Younis et al. 2003) suggests that four different monomer protein bands appearing between 36 and 31 kDa, are associated with the severity of the cow's infection response. Three out of these four bands have been identified by means of protein sequencing. Band B, with a MW of 35 kDa was identified as Panton-Valentaine leucocidin LukF'-PV chain- Staph. aureus; band C, with a MW of 32 kDa was identified as leucocidin chain LukM precursor- Staph. aureus; and band D was found to be similar, but not identical, to phosphatidylinositol-specific phospholipase-C-X. Bands B and C were purified by gel filtration using FPLC. The ability of these proteins to induce udder inflammation in vivo, and proliferation response in vitro and cytokine secretion were tested for both the crude exosecretions and purified bands. Three cows were inoculated intracisternally, with three quarters receiving either 0.007-0.008 mg (as total proteins) of Staph. aureus FR2449/1 bacterial exosecretion, pooled fraction 39-41 (bands B and C), or culture broth medium. The fourth quarter was left free as a control. Quarters that received fraction 39-41 of Staph. aureus FR2449/1, exhibited induced inflammation, which was indicated by increased somatic cell count and enhanced NAGase activity that was significantly higher than that of the original Staph. aureus FR2449/1 bacterial exosecretion. Proliferation tests of bovine blood lymphocytes in vitro showed that the pooled fraction 39-41 stimulated bovine proliferation of mononuclear cells much more than the original Staph. aureus FR2449/1 bacterial exosecretion. Secretion of TNF-alpha, IL-1beta, IL-6 and IL-8 was in accordance with the contents of LukF'-PV and LukM precursor in the exosecretions. The results suggest that LukM/ LukF' induce inflammation into the udder by a mechanism similar to that of LPS or by a unique mechanism(s) which requires further investigation.     

Reduction of anatomical noise in medical X-ray images

The X-ray pattern of a mass of very fine non-distinguishable anatomical structures alters completely from radiograph to radiograph due to the unavoidable movements of the patient during the exposure. The corresponding image component shows noise-like behaviour and is therefore referred to as the anatomical noise. Reducing this component would enhance the quality of the clinical X-ray image and increase the detectability of radiological signal. We have found that by comparing two X-ray images of the same anatomy acquired under slightly different imaging geometry, it is possible to reduce the anatomical noise in one of the image pair. The proposed method, which allows this, is based on the appropriate attenuation in the wavelet domain. The values of attenuating factors for the wavelet coefficients are proportional to the correlation between the corresponding features of both images. This method was tested for different changes in the imaging geometry. In the case of no geometrical changes, only the quantum and the electronic noise are reduced. An effect of de-noising for the investigated images is obvious.     

Immobilization of active hydrogenases by encapsulation in polymeric porous gels

Hydrogenases encapsulated in porous polymeric silica gels retain significant levels of hydrogen production activity when compared to hydrogenases in solution using reduced methyl viologen as an electron donor. Encapsulated hydrogenases remain active after storage at room temperature for longer than four weeks and are less sensitive to proteolytic digestion. Nanoscopic confinement of active hydrogenases in solids paves the way for their potential use in hydrogen producing catalytic materials applications.     

Magnetomechanical detection of the specific activities of endonucleases by cantilevers

Thiolated nucleic acids 1 or 2 are immobilized on Au-coated cantilevers and hybridized with the complementary nucleic acids 1a or 2a associated with magnetic particles. The duplexes 1/1a or 2/2a include specific sequences for the scission by Apa I or Mse I, respectively. The cantilevers positioned in a flow cell are subjected to an external magnetic field, leading to the deflection of the cantilevers. Upon the specific scission of the DNA duplexes by Apa I or Mse I, the magnetic particles are disconnected from the cantilevers leading to their retraction to the rest position. The deflection/retraction of the cantilevers are followed by a conventional atomic force microscope optical detection system.     

Role of caustics in the formation of networks of amplitude zeros for partially developed speckle fields

The topology of a partially developed speckle field was studied by use of interference techniques through computer simulation. Amplitude and phase structures in the vicinity of caustics for a coherent radiation field scattered at a surface with large inhomogeneities were investigated. It was confirmed that the caustics are indispensible components of the procedure for the formation of networks of amplitude zeros for a coherent field scattered by a rough surface with large inhomogeneities. It is shown that the formation of interference forklets in the field gives evidence of changes in the field's topology, as these forklets are a diagnostic sign of transition from a caustic to a three-dimensional pattern of a diffraction catastrophe.     

Development of alternative fuel assembly for WWER-1000 reactor

An alternative design of fuel assembly has been developed for the WWER-1000 reactor with the aim of assuring a geometrical stability of the core during operation. The fuel assembly provides enhanced safety and substantial improvement in the WWER-1000 fuel cycle economics.     

Complex radioelectronic equipment restoration cost optimization

The restoration system considered includes complex radioelectronic equipment, repair body and spares kit. The problem considered is how to optimize the total cost of the repair body and spares kit while maintaining the predetermined reliability of the radioelectronic equipment.     

Internal stress superplasticity in anisotropic polycrystalline zinc and uranium

Internal stress superplasticity is assessed in powder metallurgy and wrought polycrystalline Zn and in polycrystalline α-U. These materials are anisotropic in their thermal expansion coefficients, and, as a result, internal stresses are generated during thermal cycling. A creep model is developed based on the contribution of internal stress to the enhancement and inhibition of normal plastic flow. This creep model, which has no disposable parameters, is shown to describe quantitatively the flow behavior of anisotropic materials under thermal cycling conditions, and correctly predicts the attainment of Newtonian flow characteristics at low stresses. It is predicted that certain polycrystalline ceramics can be made superplastic in tension when thermally cycled under small applied stress.