Medical students and their views on psychiatric issues.
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Attitude to Health↗
Biomedical subjects
Y Naot
Publications and source records attributed to Y Naot.
[Cellular infiltration around basal cell carcinomas].
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Basal Cell Carcinoma↗
Induction of interleukin-2 and colony-stimulating factors in lymphoid cell cultures activated by mitogenic mycoplasmas.
Mycoplasmal infections often result in chronic inflammatory diseases that involve both local cell proliferation and chemotactic phenomena. To clarify the mechanisms responsible for these inflammatory reactions, we have examined whether nonspecific activation of host lymphocytes by mitogenic mycoplasmas triggers the production of lymphokines, which influence differentiation and proliferation of lymphocytes, macrophages and granulocytes. Mycoplasma pulmonis and M. neurolyticum were tested for their ability to induce production of interleukin-2 (IL-2) and colony-stimulating factors (CSF) by activated lymphoid cells. Mitogenic doses of membranes purified from M. pulmonis, as well as concanavalin A (ConA), induce rat lymphocytes to produce IL-2. Stimulation with the T cell mitogen ConA induces twice the level of IL-2 than does stimulation with M. pulmonis, which activates both rat B- and T-lymphocytes. Unlike these T cell mitogens, M. neurolyticum, which stimulates rat and mouse B-lymphocytes, lacks the ability to induce production of IL-2. Nevertheless, M. neurolyticum stimulates mouse spleen cells to produce in vitro factors capable of stimulating differentiation of bone marrow cells into colonies of macrophages and granulocytes.
Animals↗
Characterization of Toxoplasma gondii antigens that react with human immunoglobulin M and immunoglobulin G antibodies.
Studies were performed to define the nature of the Toxoplasma gondii antigens that are recognized by human immunoglobulin M (IgM) and IgG antibodies. Both IgM and IgG antibodies were found to be directed mainly against T. gondii membrane antigens in sera obtained from patients with acute toxoplasmosis. Treatment of the membrane preparation with DNase, RNase, or lipase had no apparent effect on the reactivity of the membrane antigens with IgM and IgG antibodies. Lipids isolated from tachyzoites were not recognized by either IgM or IgG antibodies. Exposure of T. gondii membranes to heat, proteolysis, or oxidation with sodium periodate decreased the reactivity of the membrane preparations with both IgM and IgG antibodies. A preparation of T. gondii proteins and polysaccharides were recognized by both immunoglobulin classes. T. gondii polysaccharides reacted with human IgG antibodies produced during both the acute and chronic phases of the infection. We concluded that, after infection with T. gondii, IgM and IgG antibodies are elicited in response to both protein and carbohydrate constituents of the invading parasite.
Animals↗
Microenzyme-linked immunosorbent assay for detection of immunoglobulin G and immunoglobulin M antibodies to Legionella pneumophila.
The microenzyme-linked immunosorbent assay (ELISA) for the detection of immunoglobulin M and G (IgM, IgG) antibodies to Legionella pneumophila serogroup 1 antigens was evaluated. IgM antibodies were measured by both double-sandwich and single-sandwich techniques. These assays were compared with the previously standardized indirect immunofluorescence test in four groups of subjects: (i) pneumonia patients with culture-proven Legionnaires disease with serogroup 1 isolates, (ii) pneumonia patients with serogroup 1 organisms detected by direct immunofluorescence testing of respiratory secretions but without culture confirmation, (iii) pneumonia patients with negative culture and direct immunofluorescence tests, and (iv) healthy hospital employees. In addition, the sensitivity and specificity of the IgG ELISA were evaluated with larger groups of controls and Legionnaires disease patients. The ELISA was more sensitive than the indirect immunofluorescence test. However, it detected antibody rises in pneumonia patients without culture or direct immunofluorescence evidence of L. pneumophila serogroup 1 infection, thereby suggesting that the specificity of the ELISA was slightly lower than that of the indirect immunofluorescence test. The double-sandwich ELISA was a sensitive method for detecting IgM antibodies and, as previously reported, appeared to be free from interference by rheumatoid factor. IgM anti-Legionella antibodies detected by the ELISA appeared earlier and were less persistent than IgG antibodies. In addition, the IgM ELISA was useful in detecting antibodies in necropsy serum samples obtained from patients dying acutely of Legionnaires disease. The data presented show that the ELISA is a reliable method for the detection of specific anti-Legionella antibodies.
Antibodies, Bacterial↗
Primary and reactivated toxoplasma infection in patients with cardiac transplants. Clinical spectrum and problems in diagnosis in a defined population.
We have attempted to define the serologic criteria for diagnosis of toxoplasmosis in heart transplant recipients. Of 31 patients who were seronegative before transplantation, 4 received a heart from a seropositive donor, and 3 of these 4 had seroconversion and developed life-threatening toxoplasmosis; the remaining 27 did not have seroconversion or develop clinical toxoplasmosis. Of 19 patients who had antibodies to Toxoplasma before transplantation, 10 developed significant increases in test titers of the dye test or double-sandwich IgM enzyme-linked immunosorbent assay but did not develop a clinical illness that could be attributed to toxoplasma infection. Significant serologic changes occurred more often in patients who received azathioprine, corticosteroids, and antithymocyte globulin than in those who received cyclosporine, corticosteroids, and antithymocyte globulin (p less than 0.05). These data show the wide clinical spectrum and differences in kinetics of antibody response of patients who develop toxoplasma infection after transplantation, and suggest that clinical disease occurs in those who have seroconversion but is rare in patients with preexisting antibody who have serologic evidence of recrudescence.
Dye Dilution Technique↗
IgM and IgG antibody response in two immunosuppressed patients with Legionnaires' disease. Evidence of reactivation of latent infection.
Two patients in whom pneumonia due to Legionella pneumophila developed while they were receiving immunosuppressive therapy had serologic evidence of prior infection with the same serogroup of L. pneumophila two and eight months prior to their clinical pneumonia. This suggests that the pneumonia in these patients may have been due to the reactivation of a latent infection, possibly due to their immunosuppressed state. A new enzyme-linked immunosorbent assay (ELISA) was developed to detect IgG and IgM antibodies to L. pneumophila, and the kinetics of these antibody responses were useful diagnostically.
Adult↗
Duration of IgM antibodies to Toxoplasma gondii after acute acquired toxoplasmosis.
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Acute Disease↗
[Immunological aspects of mycoplasmas infections].
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DNA↗
False-positive serological tests in heart transplant recipients.
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Antibodies↗
Use of enzyme-linked immunosorbent assays (ELISA) for detection of monoclonal antibodies: experience with antigens of Toxoplasma gondii.
The usefulness of enzyme-linked immunosorbent assay (ELISA) systems for detection of monoclonal antibodies to Toxoplasma gondii was studied. Seven monoclonal antibodies with specificities for membrane antigens, cytoplasmic antigens, or both membrane and cytoplasmic antigens of T. gondii were tested in a "sandwich" or in a "double sandwich" assay. Whereas both ELISA systems were sensitive and specific for detection of monoclonal antibodies to T. gondii, the double sandwich ELISA proved more sensitive than did the sandwich assay. Using different T. gondii antigen preparations in both assays, we demonstrated that the ELISA systems are specific, sensitive, rapid, and easy to perform and are therefore useful for screening and detection of monoclonal antibodies of desired isotypes and defined specificities.
Animals↗
IgM enzyme-linked immunosorbent assay test for the diagnosis of congenital Toxoplasma infection.
An IgM enzyme-linked immunosorbent assay, developed for detection of IgM antibodies to Toxoplasma gondii, was evaluated to define its usefulness for diagnosis of congenital Toxoplasma infection. Sera from 51 infants suspected of having congenital Toxoplasma infection but in whom this diagnosis was ruled out were negative in the IgM-ELISA test. Fifty of them were also negative in the IgM-fluorescent antibody test; the one which was positive was from an infant with congenital syphilis who had circulating rheumatoid factor. Of 55 sera from newborn infants with proved congenital Toxoplasma infection, the IgM-ELISA test was positive in 43 (72.7%), whereas the IgM-IFA test was positive in only 14 (25.4%). Of those sera obtained during the first 30 days of life the infected infants, 81.2% were positive in the IgM-ELISA test, whereas only 25% were positive in the IgM-IFA test. The Igm-ELISA test avoids the false-positive results owing to RF and the false-negative results owing to competition from high levels of maternal IgG antibody which occur in the IgM-IFA test. We conclude that the IgM-ELISA test is highly sensitive and specific for diagnosis of congenital Toxoplasma infection.
Child, Preschool↗
Mitogenicity and pathogenicity of Mycoplasma pulmonis in rats. I. Atypical interstitial pneumonia induced by mitogenic myeoplasmal membranes.
Mitogenic preparations of nonviable lysed cells and purified membranes of Mycoplasma pulmonis induced interstitial pneumonia and tracheitis after intranasal administration to pathogen-free rats. The pneumonia, characterized by peribronchial, perivascular, and alveolar wall infiltration by lymphocytes, was indistinguishable from that produced by viable M. pulmonis. Both pathologic and mitogenic effects were significanlty reduced by prior treatment of membranes with heat or proteolytic enzyme. Intranasal administration of the thymus-derived-cell mitogen, concanavalin A, produced interstitial pneumonia but not tracheitis. These results indicate a correlation of mitogenicity and pathogenicity and suggest that activation of thymus-derived lymphocytes is the major cause of the pneumonia resulting from infections with M. pulmonis.
Animals↗
Method for avoiding false-positive results occurring in immunoglobulin M enzyme-linked immunosorbent assays due to presence of both rheumatoid factor and antinuclear antibodies.
In a double-sandwich immunoglobulin M (IgM) enzyme-linked immunosorbent assay recently developed for the detection of IgM antibodies to Toxoplasma, the presence of either rheumatoid factor or antinuclear antibodies did not cause false-positive results. We recently noted, however, that in certain sera containing both rheumatoid factor and antinuclear antibodies, false-positive results do occur. In experiments to define the nature of the cross-reaction, these false-positive results were not found to be a consequence of interactions of the sera with Toxoplasma antigens, but rather were due to interactions of rheumatoid factor-antinuclear antibodies with the Fc portion of IgG antibodies used for the enzyme conjugate. This was avoided when the F(ab')2 fragment of IgG was used for the conjugate. The use of such F(ab')2 conjugates did not affect the sensitivity and, thereby, the usefulness of the double-sandwich IgM enzyme-linked immunosorbent assay for the diagnosis of acute acquired or congenital Toxoplasma infections. We concluded that F(ab')2 fragments of IgG antibodies can be used as enzyme conjugates to avoid false-positive results in sera positive for both rheumatoid factor and antinuclear antibodies in either the conventional test or in our double-sandwich IgM enzyme-linked immunosorbent assay.
Animals↗
Immunoglobulin M-immunosorbent agglutination assay for diagnosis of infectious diseases: diagnosis of acute congenital and acquired Toxoplasma infections.
An immunoglobulin M (IgM)-immunosorbent agglutination assay (IgM-IS-AGA) was negative in all sera from individuals negative in the Sabin-Feldman dye test, in sera from individuals with chronic Toxoplasma infection, and in cord blood samples from uninfected infants. In contrast, all sera that were obtained from individuals with a recent history of acute Toxoplasma infection and from infants with congenital Toxoplasma infection and that were positive in both the dye test and the IgM-indirect fluorescent-antibody (IgM-IFA) test were positive in IgM-ISAGA. A total of 21 (67.7%) of 31 sera that were negative in the IgM-IFA test, despite being obtained from individuals with recently acquired Toxoplasma infection, and 8 (72.7%) of 11 sera that were negative in the IgM-IFA test and obtained from infants with congenital Toxoplasma infection were positive in IgM-ISAGA. The presence of rheumatoid factor, antinuclear antibodies, or both did not cause false-positive results in the IgM-ISAGA but did so in the IgM-IFA test. Thus, IgM-ISAGA in both more sensitive and more specific than the IgM-IFA test for detection of IgM antibodies to Toxoplasma gondii and, therefore, for the diagnosis of acute congenital and acquired Toxoplasma infections.
Acute Disease↗
An enzyme-linked immunosorbent assay for detection of IgM antibodies to Toxoplasma gondii: use for diagnosis of acute acquired toxoplasmosis.
In an enzyme-linked immunosorbent assay (ELISA) for detection of IgM antibodies to Toxoplasma gondii, sera from individuals with negative results in the Sabin-Feldman dye test (DT) and sera from individuals with chronic toxoplasma infection all yielded negative results, even when tested undiluted. In contrast, of sera obtained from individuals with recently acquired toxoplasmosis, all sera that gave positive results in both the DT and the IgM-immunofluorescent antibody (IgM-IFA) test and 92.8% of sera that gave negative results in the IgM-IFA test yielded strongly positive results in the IgM-ELISA. Thus, the IgM-ELISA is more sensitive than the IgM-IFA test in the diagnosis of recently acquired infection with T. gondii. Moreover, sera that gave negative results in the DT but that contained either antinuclear antibodies or rheumatoid factor and thus caused false-positive results in the IgM-IFA test all yielded negative results in the IgM-ELISA, probably because serum IgM and IgG fractions were separated during the initial step.
Acute Disease↗
Mitogenic activity of Mycoplasma pulmonis. II. Studies on the biochemical nature of the mitogenic factor.
The mitogenic activity of Mycoplasma pulmonis has been demonstrated to reside in the membrane of this microorganism. Studies aimed at the identification of the membraneous mitogenic factor have revealed that membrane proteins are essential components of this mitogenic manifestation. In addition, it has been shown that the micro-organism's outer surface membrane proteins are responsible for mitogenic activity. It has been shown, however, that isolated membrane lipids are not mitogenic for rat lymphocytes and are not required for the membrane's mitogenic potential.
Animals↗
Mycoplasma neurolyticum: a potent mitogen for rat B lymphocytes.
A mitogen prepared from Mycoplasma neurolyticum has been demonstrated to induce extensive transformation of in vitro cultured rat B lymphocytes. The data summarized in this report show that rat thymus cells as well as hydrocortisone-resistant thymocytes were not activated by this mitogenic agent. On the other hand, spleen cells obtained from thymectomized, lethally irradiated and bone marrow-reconstituted rats were extensively activated by M. neurolyticum. Furthermore, M. neurolyticum was shown to induce the development of antibody-producing cells, as attested by the appearance of direct plaque-forming cells against sheep red blood cells and trinitrophenylated sheep red blood cells in spleen cell cultures exposed to this mitogen. It was also demonstrated that stimulation of rat lymphocytes by this mitogen was inhibited by anti-rat immunoglobulin antibodies. In view of these data, it was suggested that M. neurolyticum, which activates mouse B lymphocytes, is a potent mitogen for rat B lymphocytes as well. This mitogen is a significantly more powerful mitogen for rat B lymphocytes then any other known mitogens. The availability of such mitogenic material in the rat system will enable studies on control mechanisms of action and differentiation of rat B lymphocytes.
Animals↗