Cardiac tamponade: an unusual clinical presentation.

Pericardial effusion with cardiac tamponade is an unusual presentation of lymphoma, although cardiac involvement is often a late finding in widespread malignancy. Clinical identification can be difficult ante-mortem. New cardiac symptoms or classic findings of cardiac tamponade should prompt aggressive investigation. We present a case of B-cell lymphoma that initially presented as pericardial effusion with tamponade and discuss the characteristic physical findings and radiographic data that assist in diagnosis.

Rapid release and unusual stability of immunodominant peptide 45-89 from citrullinated myelin basic protein.

Myelin basic protein (MBP) exists in a population of isoforms and isomers. The 18.5 kDa MBP-C1, the main human adult isoform, has 170 residues and is relatively unmodified, whereas the same isoform can be citrullinated on six arginine residues to create the MBP-C8 (MBP Cit6) isomer. MBP Cit6 dominates in MS brain, accounting for 45% rather than 25% of the population of MBP isomers. In the fulminant form of MS, known as Marburg's Disease, 18 of the 19 arginines in MBP are citrullinated (MBP Cit18). Citrullination of MBP could lead to instability of myelin or limited remyelination. In this investigation, the susceptibilities to degradation by cathepsin D of MBP Cit6 and MBP-C1, both from normal and MS brain tissue, and Marburg MBP Cit18 were compared. The pattern of digestion was similar, and no differences of corresponding isomers in normal and MS brain were noted. However, normal MBP Cit6 was degraded 10-fold more rapidly than MBP-C1, and MBP Cit18 was degraded even more rapidly. MBP peptide 45-89 was preserved regardless of isomer type or source. Its generation was directly related to the citrulline content of the MBP substrate being 4 times faster in normal MBP Cit6 and 35 times faster in Marburg MBP Cit18 than in normal MBP-C1. Peptide 45-89 from a citrullinated MBP exhibited more deamidation, and, regardless of source, showed an alpha-helix structure in a lipid mimetic environment. We postulate that the generation of MBP peptides, including those that are dominant and encephalitogenic, is directly related to deimination of arginine to citrulline in MBP.

Citrulline-containing myelin basic protein is recognized by T-cell lines derived from multiple sclerosis patients and healthy individuals.

The cause of MS is uncertain, but an autoimmune disorder of the CNS is likely, and myelin basic protein (MBP) is a candidate antigen. MBP exists in different isoforms, generated by differential splicing of exons, and in charge isomers, generated by posttranslational modifications. Different isoforms and charge isomers presumably subserve different functions, and they vary in abundance in immature myelin found during myelinogenesis and remyelination compared with mature myelin. The 18.5-kd isomer is most abundant in normal human adults and consequently has been used almost exclusively for immunologic studies in MS. In the present study, we examined a different but abundant charge isomer of MBP, termed MBP-C8, to determine whether it could be recognized by MBP-specific cytotoxic and proliferative T-cell lines (TCL) and whether a T-cell response directed exclusively against citrulline-containing residues of MBP-C8 exists in MS patients and healthy controls. We showed that citrulline affects antigen recognition by some TCL that are specific for areas of MBP that contain the citrulline residues. Following stimulation with MBP-C8, MBP-C8-specific TCL could be generated from both MS patients and controls. T-cell responses against antigens that appear during myelinogenesis and during remyelination may be important in inducing and perpetuating an autoimmune response involved in the pathogenesis of MS.

The ethics of experimental heroin maintenance.

In response to widespread concern about illegal drug use and the associated risk of the spread of HIV/AIDS, a study was undertaken to examine whether it was, in principle, feasible to conduct a trial providing heroin to dependent users in a controlled manner. Such a trial involves real ethical issues which are examined in this paper. The general issues examined are: should a trial be an experiment or an exercise in public policy?; acts and omissions; countermobilization; termination of a trial, and payment for drugs and for a trial. The specific issues examined are: selection of trial participants; privacy; issues for staff working on a trial; coupling the trial with other treatment, and issues for researchers. A number of alternative approaches to the various ethical issues are presented and discussed.

An immunochemical comparison of human myelin basic protein and its modified, citrullinated form, C8.

An immunochemical analysis was conducted to compare the C1 isomer of human myelin basic protein (MBP) with the newly described and less cationic, citrullinated isomer of MBP referred to as C8. Ten polyclonal antisera directed at multiple epitopes or restricted regions of MBP were used in radioimmunoassays to examine MBP-C1 and MBP-C8. Antisera reactive with MBP peptide 1-14 clearly distinguished MBP-C1 from MBP-C8. Antisera to human MBP peptides 10-19 and 90-170, but not to MBP peptide 69-89, showed modest differences between MBP-C1 and MBP-C8. The MBP-C8s from multiple sclerosis (MS) and non-MS brain reacted essentially the same. With murine monoclonal antibodies and enzyme-linked immunosorbent assay (ELISA), differences between MBP-C8 and other isomers were shown for anti-MBP 10-19 but not for anti-MBP 1-9 or anti-MBP 80-89. These findings imply differences in sequence or conformation in the structure of MBP-C7 compared to MBP-C1, most notably near the amino terminus.

Monoclonal idiotypic and anti-idiotypic antibodies produced by immunization with peptides specified by a region of human myelin basic protein mRNA and its complement.

Murine monoclonal antibodies (MAbs) selective for an idiotope on a monoclonal antibody (IgG1/kappa) to human myelin basic protein (MBP) peptide 80-89 were prepared by immunization with a synthetic decapeptide specified by RNA that is complementary to the mRNA for human MBP peptide 80-89. The monoclonal anti-idiotypic antibody (anti-ID) reacted with the MAb to human MBP peptide 80-89 but not with a MAb to bovine MBP peptide 79-88 or to murine myeloma IgG1. The reaction between the monoclonal anti-ID and the MAb to the human MBP peptide 80-89 could be inhibited by human MBP peptide 80-89 and to a more limited degree with human MBP peptide 76-85 and bovine MBP peptide 79-88, but not by human MBP peptides 69-81 and 85-96. Practically, the use of a complementary peptide for stimulating an anti-ID response permits a more selective and feasible method for preparing anti-ID reagents. Theoretically, these results provide further support for the molecular basis of the network hypothesis.