Separation and characterization of polyethylene wear debris from synovial fluid and tissue samples of revised knee replacements

A study was made of in vivo-generated polyethylene wear particles as separated from synovial fluid samples and from tissue samples surrounding total knee arthroplasty. A comparison of particle size and morphology between the two particle groups was made to assess any effects of selective tissue capture, and macrophage encapsulation and digestion. In addition, a Raman spectroscopy technique was evaluated that enables positive identification of individual wear particles. The particles of the same size range found in the synovial fluid and tissue samples exhibited a comparable morphology. Notably, submicron-sized debris was present in both the synovial fluid and tissue samples surrounding knees with osteolysis. The novel micro-Raman analysis of individual particles was successful in the categorizing of wear debris as polyethylene or nonpolyethylene.

Molecular characteristics of Junin virus

Results suggest that protein, glycerophospolipid, galactoside, and sialyl glycoside residues are present in Junin virus (JV), are accessible to enzymatic digestion, and play an important role in infection. Four major protein bands with molecular masses (Mr) 64 +/- 2, 56 +/- 2, 52 +/- 3 (mean +/- standard deviation, n = 4) and approximately 12-18 kDa were consistently detected after denaturing gel electrophoresis analysis of purified attenuated JV. The 52 kDa protein showed a diffuse tail in the 52-56 kDa range and was considered to be the JV glycoprotein. By Western blotting, the 64 kDa protein bound a JV neutralizing antibody and was considered to be the viral nucleoprotein. Additional bands corresponding to larger proteins (approximately 200, 96, 86, and 78 80 kDa in size), as well as fainter and broader bands in the 23-44 kDa region were also present in purified JV preparations. The relative resistance of virus infectivity to RNase digestion demonstrates that the genome of JV is protected from enzymatic attack. Analysis of purified JV virions by electrophoresis resolved the viral small (S) RNA and large (L) RNA species, 3636 +/- 54 bases and 7667 +/- 154 bases long, respectively (average length +/- range, in four determinations). The (S) RNA of attenuated JV appeared slightly larger than that reported for a pathogenic strain, ruling out a large sequence deletion as a reason for attenuation.

Replication and physical parameters important for preparing purified Junin virus

Junin virus (JV) is an Arenavirus and the causative agent of Argentine hemorrhagic fever (AHF), an often fatal human disease. The attenuated strain XJ-clone 3 (XJC13) of JV, after being tested in humans, has been considered a promising vaccine. We found that synthesis of JV XJC13 reaches a peak 2 days after infection and the kinetics of synthesis are little affected by the multiplicity of infection (MOI) in a range from 0.125 to 1.00. Virus synthesis is sensitive to actinomycin D, indicating that cellular biosynthesis is required for viral replication. Combined precipitation and ultracentrifugation of supernatant from virus-infected cells yielded large amounts of concentrated and purified virion that banded in sucrose as a single peak with average density 1.177 +/- 0.015 g/ml. Purified virions have an average diameter of 203 +/- 23 nm by electron microscopy and an average sedimentation coefficient of 454 +/- 27 S. The results from the present study should assist in the preparation of large amounts of attenuated Junin virus which are required for vaccination against and diagnosis of Argentine hemorrhagic fever.

Detection of Junin virus by the polymerase chain reaction

Argentine hemorrhagic fever is an often fatal human disease caused by Junin virus, an RNA-containing virus and member of the Arenavirus family. This virus was detected in vitro by the polymerase chain reaction (PCR) procedure. A pair of Junin virus-specific PCR DNA oligonucleotide primers and an oligonucleotide probe were designed from a known portion of the viral RNA sequence. RNA was isolated from Junin virus-infected monkey kidney cells and used to produce complementary DNA (cDNA) by reverse transcription. A DNA segment, 151 +/- 24 bp long, was amplified from this cDNA and characterized by agarose gel electrophoresis and Southern blot hybridization with the Junin virus-specific DNA probe. Sensitivity experiments showed that Junin virus could be detected with nanogram quantities of RNA isolated from virus-infected cells. The rapid and sensitive assay described here may contribute towards the development of a procedure for the early diagnosis of Argentine hemorrhagic fever.

Method for improving accuracy of virus titration: standardization of plaque assay for Junin virus

Titrating infective virus is one of the most important and common techniques in virology. However, after many years of widespread use, the parameters governing the accuracy of titration values are still not well understood. It was found that under conditions currently used for virus titration, only a small percentage of virus in the inoculum is adsorbed onto the cells and thereby detected in the titration assay. The objective of our work was to establish the conditions for a plaque assay which could estimate more accurately the titer of Junin virus. Two different stain methods were compared and several parameters governing plaque formation were studied. The volume of the inoculum appeared as the most important factor affecting observed titer. A linear relationship between the volume of inoculum and the reciprocal apparent titer allowed us to estimate an absolute titer by extrapolation. The approach described here is likely to be applicable to the more accurate estimation of the titer of a wide range of virus.

Quantitation of poliovirus antigens in inactivated viral vaccines by enzyme-linked immunosorbent assay using animal sera and monoclonal antibodies

Recent advances in methods for the manufacture of inactivated poliovirus vaccines have resulted in increased vaccine immunogenicity. In conjunction with this capability it is important to have available highly sensitive and quantitative potency assays. The potential suitability of enzyme-linked immunoassay (ELISA) was evaluated using animal sera with neutralizing antibodies or neutralizing monoclonal antibodies for antigen detection in potency tests. The monoclonal antibodies developed, which bound D antigen but not C antigen, were neutralizing unless relatively weakly reactive. Those that bound C antigen only were non-neutralizing. Those that bound both C and D antigens were sometimes neutralizing. D-specific and D/C-specific neutralizing monoclonal antibodies against type-2 poliovirus protected mice on passive immunization against paralytic disease and death from the MEF strain virus. Potency measurements by ELISA using either D-specific neutralizing monoclonal antibodies or type-specific goat sera for antigen detection were sensitive and precise. Tests using C-specific monoclonal antibodies for antigen detection indicated that increased C antigen content may result in falsely elevated reactivities of animal sera with some vaccines. Monoclonal antibodies may be useful ELISA reagents for IPV potency testing.

Phorbol ester enhances human immunodeficiency virus-promoted gene expression and acts on a repeated 10-base-pair functional enhancer element

T-cell activation pathways are involved in the regulation of human immunodeficiency virus (HIV) expression. Phorbol 12-myristate 13-acetate (PMA) is a potent inducer of T-cell immune functions and has recently been demonstrated to increase viral replication in cell lines infected with HIV. To define sequences required for viral induction by PMA. T-cell lines were transiently transfected with viral long terminal repeat (LTR) sequences directing chloramphenicol acetyltransferase (CAT) gene expression. PMA added to transfected cell cultures 24 h before harvest reproducibly increased both CAT mRNA and enzyme expression 2- to 2-fold. Sequences necessary for basal and PMA-induced levels of CAT expression were determined by deletion and enhancer reconstitution constructs with fragments and oligonucleotides from the original LTR-CAT expression plasmid. PMA-inducible and basal activity required tandem repeats of a core enhancer element (GGGACTTTCC) located in the LTR between -105 and -82 relative to the RNA start site. The enhancerlike sequence could be inserted at a site distant to the CAT gene open reading frame and functioned in a position- and orientation-independent manner. The data thus define a transcriptionally active regulatory-enhancer element critical to the control of HIV gene expression.