Propagation velocity and attenuation of a shear wave pulse measured by ultrasound detection in agarose and polyacrylamide gels

The aim of our research was to measure and analyze phase velocity and pulse attenuation of a shear wave in two media: well-known agarose-gelatin gel and seldom-used polyacrylamide gel. These quantities were determined at three temperatures by the method of transmission sonoelastography described by Catheline et al. (1999). The shear wave was generated with a shaker stimulated by an electric pulse, with a length of one sinusoidal period with a preset frequency. The calculation method is based on a cross-correlation algorithm used for consecutive A-scans of signals of backwards scattered ultrasonic pulses. It allows determination of the local displacement of scattering elements in the medium, caused by a propagating shear wave, and determination of viscoelastic properties of gels. The results of the measurements of shear wave phase velocity and attenuation, obtained for agarose-gelatin and polyacrylamide gels that simulate biological systems depending on frequency and amplitude of vibrations, are presented. The comparison of the measured characteristic properties of gels has revealed that polyacrylamide gel is more useful in viscoelastic investigations of tissue-like phantoms.     

Fast and Precise Non-Contact Measurement of Cylindrical Surfaces with Air Gauges

In this paper, the results of an investigation on the application of air gauges in the measurement of out-of-roundness parameters are presented. The principle of the measuring system is explained, in particular the novel design of the floating gauge head. An algorithm for fully automated measurement and data processing is described. The results from a series of initial measurements provided the data for further simulations, which revealed possible sources of errors. The simulations helped to evaluate the influence of some of the parameters on the final measurement results. After various accuracy tests, the method accuracy (MA) parameter was calculated in relation to the dedicated reference form tester. The result MA = 9.29% was judged to be highly satisfactory considering the short measurement time and non-contact method.     

Viscoelastic property detection by elastic displacement NMR measurements

An attempt was undertaken to analyze the phase changes in the transverse magnetization component, M_[perp], determined in NMR response by an elastic wave in the presence of two pulses with opposite magnetic field gradient directions. The obtained theoretical results indicate that such changes are significant in biologic tissues. Their measurement by NMR opens up new possibilities for detecting the displacement and some viscoelastic properties such as the adiabatic compressibility coefficient, amplitude wave damping coefficient, frequency and dispersion strength of elastic relaxation processes, etc. The method may be useful in basic applied research and in medical diagnosis of some diseases resulting in the variation of elastic properties of biological tissues, eg, atherosclerosis.     

Leukaemias in BN/a and BN/b mice after prolonged treatment with antilymphocyte globulin

The influence of prolonged treatment with anti-lymphocyte globulin on tumour incidence in BN/a and BN/b mice was studied. One ALG sample appeared to be highly leukaemogenic in two independent experiments. All treated mice developed, after a short latency period, non-thymic lymphomas with involvement of abdominal lymph nodes and spleen resulting in ascites. Three established ascites leukaemia cell lines were examined for the presence of MuLV. In all lines viral C-type particles, soluble viral gs-1 antigen and cell surface antigen related to Gross virus were demonstrated. The mechanism of induction of these tumours remains obscure. The hypothetical role of immunosuppression, stimulation of lymphoid cells and activation of leukaemogenic virus is discussed.     

Griffithsin has antiviral activity against hepatitis C virus

Hepatitis C virus (HCV)-infected patients undergoing liver transplantation universally experience rapid reinfection of their new liver graft. Current treatment protocols do not prevent graft reinfection and, in addition, an accelerated disease progression is observed. In the present study, we have evaluated a novel strategy to prevent HCV infection using a lectin, griffithsin (GRFT) that specifically binds N-linked high-mannose oligosaccharides that are present on the viral envelope. The antiviral effect of GRFT was evaluated in vitro using the HCV pseudoparticle (HCVpp) and HCV cell culture (HCVcc) systems. We show here that preincubation of HCVpp and HCVcc with GRFT prevents infection of Huh-7 hepatoma cells. Furthermore, GRFT interferes with direct cell-to-cell transmission of HCV. GRFT acts at an early phase of the viral life cycle by interfering in a genotype-independent fashion with the interaction between the viral envelope proteins and the viral receptor CD81. The capacity of GRFT to prevent infection in vivo was evaluated using uPA(+/+)-SCID mice (uPA stands for urokinase-type plasminogen activator) that harbor human primary hepatocytes in their liver (chimeric mice). In this proof-of-concept trial, we demonstrated that GRFT can mitigate HCV infection of chimeric mice. Treated animals that did become infected demonstrated a considerable delay in the kinetics of the viral infection. Our data demonstrate that GRFT can prevent HCV infection in vitro and mitigate HCV infection in vivo. GRFT treatment of chronically infected HCV patients undergoing liver transplantation may be a suitable strategy to prevent infection of the liver allograft.     

Infrared Laser Application to Wood Cutting

While lasers are widely used across various industries, including woodworking, few studies to date have addressed the issue of cutting fresh wood. In the present investigation, wood stemming from fresh tree branches was cut at different laser powers and beam travel speeds. A fiber laser and a CO₂ laser were used for the research. The cellular structures of the cut surfaces were examined, with some of them found to be covered with a layer of compacted, charred cells. This may be a favorable phenomenon, preventing the invasion of pathogens via the wounds caused by laser beam branch cutting in nurseries, plantations, and orchards.     

Monoclonal antibody classification based on epitope-binding using differential antigen disruption

Currently, classifying a population of specific antigen-reactive monoclonal antibodies (mAbs) according to their epitope-binding properties has been limited to competition assays. Such assays are time consuming, labor intensive and restricted to the number of mAbs in the experiment. To overcome this problem, a differential antigen disruption-based antibody profiling procedure was developed. This procedure rapidly classifies specific antigen-reactive mAbs into epitope-related groups by measuring the binding signal of the antibodies to a set of structurally disrupted antigens and then clustering the antibodies according to the similarity of their binding profiles. The clustering results generated by differential antigen disruption showed a significant concordance with those generated by competition experiments. Therefore, differential antigen disruption method opens an opportunity to assess the entire population of antigen-reactive mAbs according to their epitope-binding properties. In doing so, a set of representative antibodies can be drawn to describe the epitope complexity for systematically exploring their functions.     

Altered glycosylation of membrane glycoproteins in human uroepithelial cell lines

Total cellular glycopeptides of 7 human uroepithelial cell lines that differ in the grade of transformation (TGr) were analysed by gel filtration and affinity chromatography on immobilized lectins. The 4 cell lines that are tumorigenic in nude mice and invasive in vitro (TGr III) possess more highly branched, tri- and tetraantennary N-acetyllactosaminic glycans, with less biantennary glycans than the 2 non-tumorigenic, noninvasive (TGr II) cell lines examined. The only exception to this general pattern is the third cell line, which is classified as TGr II. The cellular glycopeptide distribution pattern in this cell line is similar to that of the TGr III cells. The possible relationship between altered glycosylation of membrane glycoproteins and the expression of a malignant phenotype is discussed.