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Biomedical subjects

M A Miles

Publications and source records attributed to M A Miles.

At least 91 records · Page 5Linked to original sources
PubMed1987

Antibodies to tubulin in patients with parasitic infections.

Sera from a total of 268 patients with protozoan, helminth, bacterial (leprosy and tuberculosis) infections or appropriate controls, were assayed for anti-tubulin antibodies in an indirect enzyme-linked immunosorbent assay (ELISA), using purified tubulin as antigen. Levels of serum anti-tubulin antibody were significantly elevated in 67% of patients with visceral leishmaniasis, in 60% of patients with cutaneous leishmaniasis, in 89% of patients with onchocerciasis, in 100% of patients with schistosomiasis, and in 94% of patients with leprosy. Little or no increase in anti-tubulin antibody levels was seen in sera from patients with malaria (Plasmodium vivax) or tuberculosis.

Autoantibodies↗
PubMed1986

A biochemical comparison of glucosephosphate isomerase isozymes from Trypanosoma cruzi.

The glucosephosphate isomerase (D-glucose-6-phosphate Ketol-isomerase, EC 5.3.1.9) isozymes of Trypanosoma cruzi were characterized with respect to their native and subunit molecular size, isoelectric point and in vitro thermostability. The molecular weight data are consistent with a dimeric enzyme structure. The apparent native and subunit size homogeneity and differences in pI values imply that the electrophoretic mobility differences of isozymes in native gels are determined by their molecular charge. Minor differences in peptide maps indicate the existence of some heterogeneity in the primary structure of the isozymes. The stability of triple-banded glucosephosphate isomerase electrophoretic profiles was confirmed, supporting the view that these phenotypes represent non-interconvertible enzyme species.

Animals↗
PubMed1986

Trypanosoma cruzi: characterization and isolation of a 57/51,000 m.w. surface glycoprotein (GP57/51) expressed by epimastigotes and bloodstream trypomastigotes.

We have recently described the application of a purified glycoprotein of 25,000 Mr (GP25) of Trypanosoma cruzi in serodiagnosis of Chagas' disease. Purified GP25 lacks appreciable immunogenicity in some animal species, in spite of being generally antigenic to parasitized hosts. The underlying cause for these contrasting observations has not been determined, but it may relate to the drastic extraction conditions used in the original isolation procedure, and possible damage inflicted to the native form of this antigen. This report describes the molecular properties of a GP25-related primary antigen, and a fast performance liquid chromatographic (FPLC) procedure to attain its isolation under gentle conditions. The expression of GP25-related antigen by epimastigotes or bloodstream forms was investigated with a high-affinity monoclonal antibody to GP25, SC11G10, as well as with monospecific antisera to GP25. Immunochemical analysis of Nonidet P-40 lysates supplemented with protease inhibitors indicated that GP25 is not synthesized as such; instead, a 57,000 Mr component (GP57) was identified as the primary antigen product. Partial enzymatic conversion to GP25 was observed when inhibitors were deliberately omitted from cell extracts. Most significantly, GP57 was established as the primary biosynthetic product in [35S]-labeled bloodstream trypomastigotes after immunoprecipitation with SC11G10 antibody. This analysis when applied to metabolically labeled epimastigotes has consistently revealed a minor antigen component of 51,000 Mr (GP51), in addition to GP57. The former was identified as the antigenically related product exposed at the parasite cell surface after external radioiodination of viable trypanosomes. Access to the native form of this widely distributed surface glycoprotein should stimulate the investigation of functional and structural aspects of its immunologic activity.

Animals↗
PubMed1986

The karyotype and ploidy of Trypanosoma cruzi.

Little is known of the number or organization of chromosomes in Trypanosoma cruzi, the protozoan parasite responsible for Chagas' disease in man in the New World. Straightforward cytogenetic analysis is precluded because trypanosome chromosomes fail to condense during the cell cycle. We have size-fractionated the chromosome-sized DNA molecules of representative T. cruzi strains by pulsed field gradient (PFG) gel electrophoresis and located several housekeeping genes by Southern blotting using cDNA probes from the related trypanosome T. brucei. We show that DNA molecules from homologous chromosomes of T. cruzi migrate differently in the PFG system and infer that T. cruzi epimastigotes are at minimum diploid. In contrast to T. brucei, mini-chromosomes are absent in T. cruzi. All the housekeeping genes studied hybridize to DNA molecules which can be resolved in the PFG system, suggesting that T. cruzi may have no chromosomes larger than a few megabase pairs.

Animals↗
PubMed1986

Trypanosoma cruzi: zymodemes associated with acute and chronic Chagas' disease in central Brazil.

The clinical characteristics of acute and chronic Chagas' disease in central Brazil are described (29 acute cases and 111 chronic cases). The geographical distribution of Trypanosoma cruzi zymodemes in this region was mapped. Zymodeme (Z) 1 was identified in 12 acute cases, Z2 in 13 and repeated xenodiagnosis gave the same zymodeme identification. The clinical pictures of the Z1 and Z2 acute phases were similar. Resistance to benznidazole treatment occurred after either Z1 or Z2 acute infections. Only 14 positive xenodiagnosis were obtained from the 111 chronic phase patients examined. For 12 of these 14 patients the zymodeme was identified. All 12 carried Z2, 10 of whom had mega involvement. There were several possible explanations for the failure to detect T. cruzi Z1 in chronic Chagas' disease with mega syndromes: suggestions were made for follow-up investigations.

Adolescent↗
PubMed1986

Prevalence of antibodies to 72-kilodalton glycoprotein (GP72) in patients with Chagas' disease and further evidence of zymodeme-associated expression of GP72 carbohydrate epitopes.

Three competitive inhibition enzyme-linked immunosorbent assays were developed to examine the expression of the 72-kilodalton glycoprotein (GP72) and of a GP72 carbohydrate epitope in Trypanosoma cruzi strains and clones. A total of 148 strains and clones of known isozyme phenotype (principal zymodeme, Z) were tested. With monoclonal antibody 8G2B9 the enzyme-linked immunosorbent assay confirmed that the majority of Z1 strains and clones derived from them had undetectable levels of the carbohydrate epitope identified by antibody 8G2B9. This epitope was, however, readily detectable in all Z2, Z2(h), and Z3 strains and clones (P less than 0.001; 148 strains and clones tested). Zymodeme-associated differences in GP72 expression were not apparent from the enzyme-linked immunosorbent assay with monoclonal antibody WIC 226.4 (raised against periodate-treated GP72) or from that with rabbit anti-GP72 antiserum (84 or 119 strains and clones tested, respectively). Mice infected with culture-form metacyclic trypomastigotes of Z1, Z29, and Z3 or with blood-form trypomastigotes of Z1 and Z3 developed antibodies to affinity-purified GP72, showing that at least some GP72 epitopes are neither zymodeme specific nor stage specific. A total of 128 serum samples from patients with acute or clinically classified chronic Chagas' disease were assayed for immunoglobulin G (IgG) or IgM anti-GP72 antibodies. During the acute phase anti-GP72 IgM antibodies were elevated, whereas anti-GP72 IgG antibodies were low. There were no significant differences in anti-GP72 antibody levels among chronic-phase patient groups. Anti-GP72 antibodies were detected irrespective of the geographical origin of patients and irrespective of whether acute-phase blood parasitemias were due to Z1 (four patients) or Z2 (two patients).

Animals↗
PubMed1986

Occurrence of autoantibodies to intermediate filament proteins in human visceral leishmaniasis and their induction by experimental polyclonal B-cell activation.

Fifteen sera of patients with visceral leishmaniasis were investigated for the occurrence of autoantibodies. They were found in high incidence and titre, and with specificity to the intermediate filament (INFIL) proteins vimentin (12 out of 15 with a titre higher than 1:10) and keratin (9 out of 15 with a titre higher than 1:10) as well as to speckled anti-nuclear antigens (ANA). Additionally, supernatants of Leishmania major and Leishmania donovani cultures containing soluble parasite-derived antigens were mitogenic to cultures of mononuclear cells (MNC) obtained from healthy donors without specific antibodies to leishmanial antigens. The activation of MNC resulted in significant immunoglobulin production, some of which demonstrated autoantibody specificity to INFIL. The co-operation of monocytes, T cells and B cells was required in order to obtain maximal stimulation. The importance of polyclonal B-cell activation for the genesis and occurrence of autoantibodies in visceral leishmaniasis is discussed.

Antigens, Protozoan↗
PubMed1985

Immunodiagnostic detection of Giardia antigen in faeces by a rapid visual enzyme-linked immunosorbent assay.

An enzyme-linked immunosorbent assay (ELISA) was developed for the detection of Giardia antigen in human faeces. 136 faecal samples were tested; 76 were positive and 27 negative for giardia cysts on microscopy, and 33 samples contained a range of other parasites. The ELISA sensitivity exceeded 98% and its specificity was 100%, by both colorimetry and direct visual interpretation. The assay could trace the decline and disappearance of antigen in faeces rendered microscopically negative by chemotherapy. This ELISA, which can be completed in less than 3 h and which does not rely on complex equipment for interpretation, should be very useful in diagnostic and epidemiological applications.

Antigens, Protozoan↗
PubMed1985

A focus of mucocutaneous leishmaniasis in Três Braços, Bahia, Brazil: characterization and identification of Leishmania stocks isolated from man and dogs.

The characterization and identification to species and subspecies of 20 stocks of Leishmania isolated from the region of Três Braços, Bahia, Brazil, are described: 17 stocks were from patients and three from dogs. The following techniques were used (i) biological (growth in culture, hamster tissues and phlebotomine gut), (ii) biochemical (isoenzyme and kinetoplast DNA analysis) and (iii) immunological (using monoclonal antibodies). All except two stocks belong to the L. braziliensis complex. One of these two corresponded to L. mexicana amazonensis but the other, while clearly in the mexicana complex, showed slight differences from the L. mexicana amazonensis reference strain on isoenzyme analysis. Two stocks from different lesions in the same patient and with different growth characteristics in hamster tissues were both identified as L. braziliensis braziliensis. All the fully characterized stocks of the L. braziliensis complex were identified as L. braziliensis braziliensis. L. braziliensis guyanensis was not identified. Dog and human stocks of L. braziliensis braziliensis were indistinguishable. From these findings and other evidence, L. braziliensis braziliensis seems to be the predominant species transmitted in Três Braços.

Animals↗
PubMed1985

Further evaluation of lectin affinity purified glycoprotein (GP90) in the enzyme linked immunosorbent assay (ELISA) for diagnosis of Trypanosoma cruzi infection.

Sera from 143 patients considered to be infected with Trypanosoma cruzi on the basis of epidemiological, clinical and standard serological evidence gave positive results in the enzyme-linked immunosorbent assay (ELISA) using a lectin affinity purified 90,000 molecular weight glycoprotein (GP90) antigen preparation. Levels of antibody did not discriminate between clinically classified groups of patients in the chronic phase of infection. The GP90 preparation was found to be heterogeneous.

Adolescent↗
PubMed1985

Isozyme profiles of Trypanosoma cruzi stocks from Colombia and Ecuador.

A total of 74 of 82 domestic Rhodnius prolixus from the same locality in eastern Colombia were found to be infected with Trypanosoma cruzi or T. rangeli. One of three domestic Triatoma dimidiata from Ecuador also showed T. cruzi infection. A total of 59 T. cruzi stocks from these and five other localities in Colombia were isolated from man, marsupials and triatomine bugs. Cellulose-acetate electrophoresis of nine or ten enzymes characterized all T. cruzi stocks as zymodeme 1 (reference clone Silvio X10/1). Differences in electrophoretic patterns between the newly isolated stocks and the zymodeme 1 standard were seen with the enzymes G6PD and HK. These results are in agreement with the previously described geographical distribution of T. cruzi zymodemes. Stocks were isolated from both low and high altitudes and there was no evidence of adaptative significance of T. cruzi enzyme polymorphism.

Animals↗
PubMed1985

Flagellate infections of Brazilian sand flies (Diptera: Psychodidae): isolation in vitro and biochemical identification of Endotrypanum and Leishmania.

Flagellate infections were found in 1,063 of 18,895 sand flies collected in the states of Amazonas, Pará, Rondonia and Acre, Brazil. Infection rates were 13.4% (species group Shannoni); 7.5% (subgenus Nyssomyia); 6.7% (subgenus Lutzomyia series Cruciata); 0.5% (genus Psychodopygus) and 3.1% for other sand flies (various subgenera). Leishmania braziliensis guyanensis and L. mexicana amazonensis were isolated, respectively, from the known vectors, Lutzomyia umbratilis and L. flaviscutellata. Single stocks of L. braziliensis-like and L. mexicana-like organisms were isolated, respectively, from L. whitmani and L. yuilli. Thirty-eight flagellate stocks, isolated by direct culture from sand flies were characterized in detail by morphology in culture, behavior in hamsters and mice and by enzyme profiles. Sixteen stocks from Lutzomyia sp. (Shannoni group) were identified as Endotrypanum schaudinni; 8 stocks from Lutzomyia sp. (Shannoni group) were identified as Endotrypanum sp.; 7 stocks from Psychodopygus ayrozai and P. paraensis were identified as Leishmania sp. previously isolated from the armadillo, Dasypus novemcinctus; 2 stocks of Trypanosoma rangeli were isolated from recently fed Lutzomyia sp. (Shannoni group) sand flies; the remaining 5 stocks from L. umbratilis and L. yuilli could not be identified. Observations suggested that Shannoni group sand flies were the natural vectors of Endotrypanum. Leishmania sp. infections in the man-biting flies P. ayrozai and P. paraensis were restricted to the midgut and associated with recent bloodmeals. Unidentified flagellates in L. umbratilis and L. yuilli were distributed throughout the digestive tract with no trace of bloodmeals.

Animals↗