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Biomedical subjects

E J Shannon

Publications and source records attributed to E J Shannon.

12 recordsLinked to original sources
PubMed1992

Thalidomide's effectiveness in erythema nodosum leprosum is associated with a decrease in CD4+ cells in the peripheral blood.

Thalidomide is well documented as being an effective drug in the treatment of erythema nodosum leprosum (ENL). The mechanism of action of thalidomide in ENL as well as the pathogenesis of ENL are yet to be fully determined. Lepromatous leprosy patients experiencing ENL have been reported to have an increase in the ratio of CD4+ to CD8+ cells in their blood and ENL skin lesions. Thalidomide has been shown to cause a decrease in the ratio of CD4+ to CD8+ lymphocytes in the blood of healthy males. This decrease was due to a significant reduction in the numbers of Cd4+ lymphocytes and an apparent increase in the numbers of CD8+ lymphocytes. In this study, thalidomide's effectiveness in halting chronic ENL and arresting a relapse into ENL was consistently associated with a decrease in the numbers of CD4+ lymphocytes in the blood of 2 male lepromatous leprosy patients.

Adult↗
PubMed1992

Competency of human-derived Mycobacterium leprae to use palmitic acid in the synthesis of phenolic glycolipid-I and phthiocerol dimycocerosate and to release CO2 in axenic culture.

Insufficient numbers of viable Mycobacterium leprae have hampered metabolic studies using human-derived M. leprae. In this study, sufficient numbers of M. leprae were obtained from an untreated lepromatous patient to titrate the effects of pH on the metabolism of 14C-palmitic acid by M. leprae. Catabolic metabolism (oxidation of 14C-palmitic acid and release of 14CO2) was maximal when M. leprae were incubated at 33 degrees C and suspended in Middlebrook 7H9, ADC supplemented medium that had been buffered to maintain a pH of 4.8. Anabolic metabolism (synthesis of 14C-phenolic glycolipid-I and its precursor, 14C-phthiocerol dimycocerosate) was maximal when the pH was maintained at 6.8.

Adolescent↗
PubMed1990

Confirmation of a false-positive result associated with a competition inhibition assay used for detecting antibodies to a protein epitope of Mycobacterium leprae.

A competitive antibody-binding assay (CABA) was developed to detect antibodies in infected armadillos and leprosy patients which compete with an M. leprae-specific 125I monoclonal antibody IIIE9 for the species-specific M. leprae-IIIE9 epitope on the 65-kD protein. The results suggest armadillos and leprosy patients produce antibodies that inhibit the binding of 125I-IIIE9 monoclonal antibody to the IIIE9 epitope on crude, native 65-kD protein preparations. When purified, recombinant 65-kD protein was substituted for crude antigen, there was no evidence in the CABA of antibody to the IIIE9 epitope. False-positive results, possibly induced by steric hindrance, are likely to be associated with CABA which incorporate crude cell wall extracts as solid-phase antigen.

Animals↗
PubMed1990

The evolution of antibody response in armadillos inoculated with Mycobacterium leprae.

Plasma from 30 armadillos (Dasypus novemcinctus) was collected prior to inoculation and at approximately 3-month intervals for a period of 1-3 years. These animals were inoculated intravenously with 6.1 x 10(8) +/- 2 x 10(8) (x +/- SD) armadillo-derived Mycobacterium leprae. These samples were analysed for antibodies of IgM and IgG class to phenolic glycolipid-I (PGL-I) and to sonicated M. leprae components using ELISA and immunoblotting techniques, respectively. We had previously observed among a group of 11 armadillos, that some animals produced and maintained a high IgG antibody response to PGL-I. In this study, an animal's ability to produce and maintain an elevated IgG anti-PGL-I response was significantly correlated with their ability to delay dissemination of the infection and their ability to survive longer. When the animals were moribund, a significant decrease in the IgG anti-PGL-I absorbance value was observed. The detection of PGL-I in the plasma samples collected from moribund armadillos suggested that high concentrations of PGL-I in the plasma may have contributed to a drop in absorbance values by the formation of non-lattice-type immune complexes in vivo. As detected by immunoblotting, the IgM and IgG response to antigens derived from sonically disrupted M. leprae was directed towards molecules with broad bands of immunoreactivity ranging from 21- to 45-kDa. There were no distinguishing features of these antibody responses among armadillos as was evident with the IgG anti-PGL-I responses.

Animals↗
PubMed1988

Partial characterization of antigens from M. leprae evoking IgG and IgM antibodies in armadillos.

Armadillo IgG and IgM antibody responses to Mycobacterium leprae were analyzed using isotypic-specific antisera by means of immunoblotting. Blots developed for IgG antibodies to M. leprae showed multiple protein antigens (Mr = 12-90 K) in some heavily infected armadillos. In contrast, blots developed for IgM antibodies to M. leprae showed a single, broad, diffuse band of immunoreactivity at approximately 33 kDa. The 33-kDa immunogen was detectable with silver stain modified for carbohydrate reactivity, suggesting the presence of a polysaccharide component. In addition, binding of 125I-concanavalin A to the 33-kDa component demonstrated the presence of mannose and/or glucose residues.

Animals↗
PubMed1988

Armadillo IgG and IgM antibody responses to phenolic glycolipid-I during experimental infection with M. leprae.

The kinetics of antibody responses of Mycobacterium leprae-infected armadillos to phenolic glycolipid-I (PGL-I) were studied by means of ELISA. The levels of both IgG and IgM antibodies to PGL-I increased with time. Some animals were less susceptible to disseminations of M. leprae infection and lived longer than others. These animals had high absorbance values (greater than 0.7) for IgG anti-PGL-I compared to more susceptible armadillos that had lower absorbance values for IgG anti-PGL-I.

Animals↗
PubMed1987

Adoptively transferred reactivity to M. leprae in nude mice infected with M. leprae.

Reversal reactions are manifestations of delayed hypersensitivity to M. leprae and are thought to be usually accompanied by manifestations of effective cell-mediated immunity (CMI) as measured by bacterial clearing. These experiments were designed to study the induction of reversal reactions in M. leprae-infected, congenitally athymic nude mice using adoptive transfer of CMI. Splenic cell suspensions derived from unimmunized heterozygous nu/+ mice, and those vaccinated with heat-killed M. leprae, viable BCG and a mixture of the two antigens were diluted to contain 10(4), 10(5), 10(6), 10(7) lymphocytes/0.1 ml and infused intravenously into multibacillary nude mice. The production of reversal reactions in leprous nude mice in response to adoptively transferred CMI was studied in a quantitative fashion. Dose responsive induction of reversal reactions, apparent by footpad inflammation and swelling, decreased morphological indices (MI) of the bacteria and mononuclear cell infiltrations, histopathologically, were observed. For nude mice receiving cells primed with 3.9 X 10(5) living BCG alone, the effective dose 50% (ED50) was 1.0 x 10(6) lymphocytes to induce reversal reactions. For those receiving cells primed with 10(7) M. leprae the ED50 was 3.7 x 10(5) lymphocytes. For nude mice receiving cells primed with a mixture consisting of 1/2 the above dose of BCG + 1/2 the above dose of M. leprae, the ED50 was 6.8 x 10(4) lymphocytes.

Animals↗
PubMed1977

Methods for the identification of human B lymphocytes.

Complement-receptor lymphocytes and monocytes were identified by a rosette method using trypsin treated sheep erythrocytes (Et), sensitized with affinity column purified IgM (19S) antibodies against sheep erythrocytes (E) and mouse complement deficient in C5. Fc receptor mononuclear cells were identified by a rosette method using Et and IgG (7S) antibodies against E. Identification of the cell-type rosetting was facilitated by myeloperoxidase staining of dry mounted rosetted preparations. Comparison of lymphocytes with receptors for activated mouse complement and lymphocytes with stable surface immunoglobulin detected by immunofluorescent assay, strongly suggests that these cells constitute the same population in the peripheral blood of healthy humans.

Animals↗