Print Profile Research Articles

Association of deficiency in antibody response to vaccine and heterogeneity of Ehrlichia risticii strains with Potomac horse fever vaccine failure in horses.

Ehrlichia risticii is the causative agent of Potomac horse fever (PHF), which continues to be an important disease of horses. Commercial inactivated whole-cell vaccines are regularly used for immunization of horses against the disease. However, PHF is occurring in large numbers of horses in spite of vaccination. In a limited study, 43 confirmed cases of PHF occurred between the 1994 and 1996 seasons; of these, 38 (89%) were in horses that had been vaccinated for the respective season, thereby clearly indicating vaccine failure. A field study of horses vaccinated with two PHF vaccines indicated a poor antibody response, as determined by immunofluorescence assay (IFA) titers. In a majority of horses, the final antibody titer ranged between 40 and 1,280, in spite of repeated vaccinations. None of the vaccinated horses developed in vitro neutralizing antibody in their sera. Similarly, one horse experimentally vaccinated three times with one of the vaccines showed a poor antibody response, with final IFA titers between 80 and 160. The horse did not develop in vitro neutralizing antibody or antibody against the 50/85-kDa strain-specific antigen (SSA), which is the protective antigen of the original strain, 25-D, and the variant strain of our laboratory, strain 90-12. Upon challenge infection with the 90-12 strain, the horse showed clinical signs of the disease. The horse developed neutralizing antibody and antibody to the 50/85-kDa SSA following the infection. Studies of the new E. risticii isolates from the field cases indicated that they were heterogeneous among themselves and showed differences from the 25-D and 90-12 strains as determined by IFA reactivity pattern, DNA amplification finger printing profile, and in vitro neutralization activity. Most importantly, the molecular sizes of the SSA of these isolates varied, ranging from 48 to 85 kDa. These studies suggest that the deficiency in the antibody response to the PHF vaccines and the heterogeneity of E. risticii isolates may be associated with the vaccine failure.

Indentation at the Nanometer Scale on Ultra Thin Films of Diamond-Like Carbon

AbstractUltra thin films (50 nm and 180 nm) of amorphous diamond-like carbon on a silicon substrate produced by laser ablation are tested by nanoindentation with a new instrument deriving from a Surface Force Apparatus. Quasi-static measurements of the load and dynamic measurements of the contact stiffness are continuously and simultaneously recorded versus the penetration depth. Scanning lines on the tested surface before and after indentation are made by means of tangential displacement of the diamond indenter on the surface.The tests are conducted with maximum loads from 50 μN to 2500 μN, which correspond to maximum indentation depths between 7 nm and 70 nm. The indentation curves show near elastic recovery but scanning lines and/or topographic images on the surfaces show detectable plastic prints. Despite the extremely small residual indentation depths for these ultra thin films, we show how the hardness value we calculate from the indentation curves with an elastoplastic theory is in good agreement with the hardness value we calculate from the indentation print profile. The determination of the Young's modulus, even at the smallest indentation depths, must take into account the mechanical properties of the substrate. The determination of both values, hardness and elastic modulus, also requires a calibration procedure for the geometry of the tip and knowledge of the piling-up effect.We find that the apparent hardness and the apparent Young's modulus of the tested diamondlike films are high. They are underestimated in comparison with the real values. A rough correction which overestimates the Young’s modulus gives higher values than those of natural diamond.

Two Cases of Juvenile Type Generalized Ceroid‐Lipofuscinosis: An Ultrastructural Study of Storage Material

The clinical course, distribution and morphology of the characteristic inclusions in two cases of generalized ceroid‐lipofuscinosis of juvenile type were investigated. The first case was a Japanese man who died aged 21. He developed visual disturbances at the age of 6 years, and became blind within a year. Epileptic seizures and dementia progressed from the age of 12. The second case was a Japanese woman who also died aged 21 years. She developed dementia, convulsions and visual disturbances at the age of 6 years and progressed gradually. She became almost completely blind at the age of 14 years. In both of the cases, the autopsy revealed diffuse atrophy of the brain. The histology showed numerous lipofuscin‐like granules in the swollen cytoplasm of nerve cells and astrocytes. The storage materials revealed four distinct ultrastructural profiles as follows; 1) multilamellar body (MLB), 2) curvilinear body (CB), 3) crystalloid profile (CP), 4) finger print profile (FPP). The distribution of these storage materials in both central and peripheral nervous system and in various tissue of the body was studied systematically and shown in a table.

Nonspecific structures seen in diagnostic muscle biopsies

In a period of two years we have analyzed 50 muscle biopsies using the transmission electron microscope. Six nonspecific structures consisting of filamentous bodies, tubular aggregates, paracrystalline mitochondrial inclusions, honeycomb arrays, concentric laminated bodies, and finger print profiles were observed in 47 of 50 cases. In order to know the significance of these structures in muscle biopsies, we correlated their occurrence with their clinical history, histological findings, and histochemistry.The biopsies were initially fixed in 2.5% glutaraldehyde (pH. 7.5, 500 mOsm), then randomly minced and post fixed in 1% osmium tetroxide. All biopsies were processed with and without uranyl acetate en bloc staining in Walpole's buffer before ethanol dehydration. They were embedded in Epon 812 epoxy resin, sectioned, and stained with uranyl acetate and lead citrate before evaluation with a JEOL, JEM 100 C Transmission Electron Microscope. All grid squares of six different blocks were scanned to evaluate the ultra-structural pathology.