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Biomedical subjects

L Georgescu

Publications and source records attributed to L Georgescu.

At least 19 recordsLinked to original sources
PubMed1999

Lymphoma in patients with rheumatoid arthritis: what is the evidence of a link with methotrexate?

An increasing number of instances of lymphoma in patients with rheumatoid arthritis who are treated with methotrexate continue to appear. The majority of patients with lymphoproliferation have features of immunosuppression-associated lymphoma. Rheumatoid arthritis itself and the actions of methotrexate concur in leading to a immunosuppressed state. Possible oncogenic mechanisms and the risk factors for patients with rheumatoid arthritis to develop lymphoma while receiving methotrexate include: (i) intense immunosuppression and severe disease in combination with genetic predisposition and; (ii) an increased frequency of latent infection with prooncogenic viruses like Epstein-Barr virus. The aetiological role of methotrexate in the development of these lymphomas is supported by the spontaneous remission of these malignancies in some of patients with rheumatoid arthritis after methotrexate has been stopped. The physicians caring for patients with rheumatoid arthritis receiving methotrexate should be vigilant about signs and symptoms suggestive of lymphoma, mostly in those patients with significant comorbidity, long standing and severe disease who are more likely to be immunosuppressed. If a lymphoma appears in these patients, methotrexate should be stopped. Spontaneous remission may occur and a period of observation is advisable when clinically possible. If functional deterioration appears or there are signs of lymphoproliferative organ invasion after several months then specific antineoplastic treatment should be instituted.

Adult↗
PubMed1997

Interleukin-10 promotes activation-induced cell death of SLE lymphocytes mediated by Fas ligand.

Immune function in SLE is paradoxically characterized by active T cell help for autoantibody production, along with impaired T cell proliferative and cytokine responses in vitro. To reconcile these observations, we investigated the possibility that the accelerated spontaneous cell death of SLE lymphocytes in vitro is caused by an activation-induced cell death process initiated in vivo. 27 SLE patients, three patients with systemic vasculitis, seven patients with arthritis, and 14 healthy subjects were studied. Patients with clinically active SLE or systemic vasculitis had accelerated spontaneous death of PBMC with features of apoptosis at day 5 of culture. A prominent role for IL-10 in the induction of apoptosis was observed, as neutralizing anti-IL-10 mAb markedly reduced cell death in the active SLE patients by 50%, from 22.3 +/- 5.2% to 11.2 +/- 2.8%, and the addition of IL-10 decreased viability in the active SLE group, but not in the control group, by 38%. In addition, apoptosis was shown to be actively induced through the Fas pathway. The potential clinical relevance of T cell apoptosis in active SLE is supported by the correlation of increased apoptosis and IL-10 levels in vitro with low lymphocyte counts in vivo. We conclude that the spontaneous cell death observed in vitro in lymphocytes from patients with SLE and other systemic autoimmune disorders results from in vivo T cell activation, is actively induced by IL-10 and Fas ligand, and reflects pathophysiologically important events in vivo. Activation-induced cell death in vivo provides a pathogenic link between the aberrant T helper cell activation and impaired T cell function that are characteristic features of the immune system of patients with SLE.

Adult↗
PubMed1997

Anti-P antibodies and neuropsychiatric lupus erythematosus.

A high proportion of patients with SLE develop neuropsychiatric lupus during the course of their disease. The expression of disease varies significantly in terms of clinical manifestations, onset, and severity, so that this form of lupus remains a major diagnostic and therapeutic challenge. Because affected tissue cannot be sampled and animal models are not readily available, scientific investigation is considerably hampered. Approximately 15% of lupus patients have anti-P antibodies. These autoantibodies are highly specific for SLE. Most series show a highly significant association between anti-P and lupus psychosis, and this result is now confirmed in a series of 336 SLE patients. The mechanism explaining this association is uncertain and may simply reflect an immune response to damaged tissue. However, the possibility that the antibodies are pathogenic by directly binding to cell-surface receptors on neuronal cells or that they penetrate cells and inhibit protein synthesis within the cell requires further investigation. Whether T cells are involved in the pathogenesis of CNS disease is an important question that has received little attention. As in the CNS of patients with multiple sclerosis and patients with other autoimmune diseases, excess production of cytokines may contribute significantly to organ inflammation. We report associations between anti-P autoantibodies and certain MHC class II alleles, particularly HLA-DQB1*0602. These findings support a role for T cells in anti-P autoantibody production and encourage further studies of the role of autoantigen-specific T and B cells in injury to the central nervous system.

Autoantibodies↗
PubMed1997

Lymphoma in patients with rheumatoid arthritis: association with the disease state or methotrexate treatment.

Although long-term clinical studies have shown no excessive risk of lymphoma in rheumatoid arthritis (RA) patients treated with methotrexate (MTX), an increasing number of reports of this association continue to appear. We describe two cases, review the cases in the world's literature, and summarize their important characteristics. Possible oncogenic mechanisms are discussed. Most lymphoproliferation cases presented here have features of immunosuppression-associated lymphoma. The immunosuppressed state is attributable to a combination of factors, such as RA itself and the actions of MTX. The risk factors for RA patients to develop lymphoma while on MTX include severe disease, intense immunosuppression, genetic predisposition, and an increased frequency of latent infection with prooncogenic viruses such as Epstein-Barr virus (EBV). The spontaneous remission of lymphomas in eight RA patients after MTX was stopped highlights the likely causative role of the drug in the development of these malignancies. If the clinical situation permits, a period of observation for spontaneous remission after MTX is stopped is advisable. The physicians caring for RA patients on MTX should maintain a high surveillance for signs and symptoms suggestive of lymphoma.

Aged↗
PubMed1997

The co-occurrence of acute rheumatic fever and AIDS.

We describe a patient with advanced acquired immunodeficiency syndrome (AIDS) who presented with evidence of carditis, arthritis, and chorea in the setting of fever, and serologic evidence for recent streptococcal infection. Several features atypical for rheumatic fever were present and included persistently high titer of antistreptolysin O, the simultaneous occurrence of chorea and arthritis, and the presence of chorea in a sexually mature adult man. The differential diagnosis of arthritis in a host at risk for human immunodeficiency virus should be expanded to include acute rheumatic fever, which may manifest atypical features.

Acquired Immunodeficiency Syndrome↗
PubMed1996

Ribosomal P autoantibodies in systemic lupus erythematosus. Frequencies in different ethnic groups and clinical and immunogenetic associations.

OBJECTIVE: To determine the frequencies and clinical associations of antiribosomal P antibodies (anti-P) in a large multiethnic cohort of patients with systemic lupus erythematosus (SLE), and to assess whether anti-P was associated with any major histocompatibility complex (MHC) class II alleles or shared amino acid sequences. METHODS: Sera from 394 SLE patients were studied for anti-P using an enzyme-linked immunosorbent assay, and MHC class II alleles (HLA-DRB1, DQA1, and DQB1) were determined by DNA oligotyping. RESULTS: Anti-P antibodies were found in 13-20% of patients in the majority of ethnic groups, but were perhaps more frequent in Chinese patients (36%) and less common in Bulgarian patients (6%). Neuropsychiatric lupus (psychosis and/or depression) was significantly associated with anti-P. The HLA-DR2, DQ6 haplotypes DRB1*1501 or *1503, DQA1*0102, and DQB1*0602 were increased in anti-P-positive whites, blacks, and Mexican Americans. The HLA-DQB1*0602 allele showed the strongest association with anti-P when these 3 ethnic groups were combined and compared with both race-matched anti-P-negative SLE patients and normal controls. The HLA-DQ8 specificity (DQB1*0302) was increased both in whites and in Mexican-Americans with anti-P who were negative for HLA-DQB1*0602, and perhaps also increased in Greeks, but not in blacks, in whom HLA-DQB1*0301 was increased. A shared amino acid sequence in HLA-DQB1 (at position 26 of leucine and position 30 of tyrosine) was strongly associated with anti-P positivity (70%) versus anti-P negativity (42%) across ethnic lines. CONCLUSION: The anti-P response in SLE patients, occurring in approximately 15% of patients, was strongly influenced by certain MHC class II alleles and was correlated with diffuse neuropsychiatric dysfunction.

Black or African American↗
PubMed1994

The use of severe combined immunodeficiency mice to study the metabolism of human immunoglobulin G.

BACKGROUND: Although the four human immunoglobulin G (IgG) isotypes are similar in structure, they exhibit significant differences in effector function and catabolic half-life. With advent of structurally engineered antibodies, there is the potential to design antibody constructs with desired half-lives; however, it is first necessary to discover the structures and mechanisms that control immunoglobulin metabolism. METHODS: Radioiodinated chimeric antibodies, consisting of a mouse antidansyl variable region and the four human IgG constant regions, were injected intravenously into Balb/c and severe combined immunodeficiency (SCID) mice, and their half-lives were determined by whole body and whole blood counting. Dependence of the rate of immunoglobulin catabolism on immunoglobulin concentration, a normal regulatory phenomenon specific to IgG, was evaluated by the introduction of large amounts of human gamma-globulin intraperitoneally. RESULTS: Whole body and blood half-lives were statistically indistinguishable. The four IgG isotypes were eliminated from the whole animals in a predominantly single-phasic manner, with the half-life being dependent on the isotype studied. In Balb/c mice, immune elimination frequently occurred after 6 days, although this was not observed in SCID mice. Relevance of the model was confirmed by the demonstration of the presence of the concentration-catabolism phenomenon, a relationship unique to normal IgG regulation. CONCLUSIONS: SCID mice provide an adequate initial animal model for the study of human-mouse chimeric antibodies. Further understanding of the factors governing immunoglobulin catabolism can be probed by study of recombinant human constant regions in this animal system.

Animals↗
PubMed1983

Tubular structures occurring in cells infected with herpesviruses.

Certain viruses belonging to the Herpesviridae family generate tubular structures of three distinct size ranges late in the growth cycle. The smallest tubules are about 10 to 20 nm in diameter, and are restricted to the cell nucleus, tending to form palisades of lattice-like structures. The medium sized tubular structures are about the width of a core particle, measuring 55 to 65 nm in diameter, while the larger tubular structures are the same diameter as viral capsids, about 80 to 100 nm. Both are rigid capsomered structures, which are sometimes encountered outside the cell nucleus budding onto spherical particles. The available data on some properties of the various tubular structures, as well as speculations concerning their nature and significance are briefly reviewed. Their importance is emphasized for antigen and vaccine production, as well as in differentiating herpesviruses by electron microscopy.

Animals↗
PubMed1981

Sudden disappearance and reappearance of the pathologic Q waves after successive myocardial necrosis: electrocardiographic and pathologic correlations.

A case with sudden disappearance of the pathologic Q waves of an old posterior myocardial infarction after a superimposed acute anterior infarction is reported. This phenomena probably is due to the loss of the opposing electromotive forces in the anterior myocardial wall after acute anterior myocardial necrosis. When a third acute lateral myocardial infarction occurred, new Q waves in the corresponding leads could be observed. Pathologic examinations documented three temporally and spaciously separate infarctions. Such correlations allow a better understanding of the electrocardiographic changes in patients with successive myocardial infarctions.

Electrocardiography↗
PubMed1976

[Fibrosarcoma of the orbit (author's transl)].

During a period of 8 months a capsulated orbital tumour--not adherent the orbital walls or the bulbus--developed in a 21-year-old female patient. The tumour was exstirpated in toto. The histological findings show a fibrosarcoma with poorly differentiated cells, giant cells and numerous mitoses. The comparatively small incidence of the tumour as well as the prognosis quoad vitam are discussed.

Adult↗