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H L David

Publications and source records attributed to H L David.

At least 37 records · Page 2Linked to original sources
PubMed1990

Conjugative transfer of a shuttle plasmid from Escherichia coli to Mycobacterium smegmatis [corrected].

The chimeric plasmid pMY10 containing the origin of replication of pAL5000, the origin of replication of pBR322, the origin of transfer of pRK2 and a kanamycin resistance gene was constructed and successfully transferred by conjugation from Escherichia coli harbouring the helper plasmid pRK4.24 into Mycobacterium smegmatis. This is the first report of conjugtive transfer of plasmid between E. coli and an acid fast organism.

Blotting, Southern↗
PubMed1990

IgG and IgM antibodies immunoreacting with a 2,3-diacyl trehalose-2'-sulphate in sera from leprosy patients.

The distribution of IgG and IgM antibodies immunoreacting with the sulpholipid I (SLI) and sulpholipid IV (SLIV) of Mycobacterium tuberculosis was examined in sera from leprosy patients. It was found that the immunological reactions correlated with the clinical spectrum of leprosy; and in multibacillary patients, antibody titres declined in response to successful treatment. The serological patterns were similar to the PGL I patterns, however, the IgG responses towards the sulpholipids were predominant over the IgM responses in the case of the sulpholipid antigens.

Antibodies, Bacterial↗
PubMed1990

Enhancement of drug susceptibility of Mycobacterium avium by inhibitors of cell envelope synthesis.

Treatment of infections caused by Mycobacterium avium complex bacteria still remains a challenge since these organisms are resistant to a majority of antituberculous drugs. M. avium is very often linked with acquired immune deficiency syndrome-associated opportunistic infections. We earlier suggested that one of the strategies for circumventing multiple-drug resistance might be the enhancement of M. avium drug susceptibility by inhibiting the synthesis of the outermost layer of its envelope, which appears to act as an exclusionary barrier for drugs. In this investigation, we have examined this strategy by simultaneously using drugs and the following inhibitors of the M. avium cell envelope: m-fluoro-phenylalanine (an inhibitor of mycoside-C biosynthesis), DL-norleucine (an inhibitor of transmethylation reactions), ethambutol (an inhibitor of arabinogalactan synthesis), EDTA (a divalent-ion chelator), and colistin (an inducer of membrane flux of divalent cations). All the drugs were used in concentrations which were low enough for a possible medical application to be foreseen. This approach, tested on seven strains of the M. avium complex, showed that both m-fluoro-phenylalanine and ethambutol were interesting candidates because they caused significant enhancement of M. avium drug susceptibility.

Anti-Bacterial Agents↗
PubMed1989

Antigenicity and specificity of selected glycolipid fractions from Mycobacterium tuberculosis.

Antigenicity of Mycobacterium tuberculosis glycolipids polyphthienoyl trehalose (PPTR), phenolic glycolipid (PGL-Tb1), tetraacyl trehalose-2'-sulphate (SL-I) and diacyl trehalose-2'-sulphate (SL-IV) was examined in rabbits. PPTR did not induce production of IgG antibodies in rabbits, while PGL-Tb1, SL-I and SL-IV glycolipids were efficient in this respect. Immune sera raised in rabbits immunoreacted exclusively with the corresponding antigens, which indicated that they were remarkably specific. Specificity of the immune sera was further examined using crude extracts of representative strains of 39 mycobacterial species, and the data showed that these immune sera reacted only with extracts of M. tuberculosis and M. africanum. An antiserum raised against whole cells of M. leprae immunoreacted with the purified SL-IV antigen from tubercle bacilli.

Animals↗
PubMed1989

Ability of smooth and rough variants of Mycobacterium avium and M. intracellulare to multiply and survive intracellularly: role of C-mycosides.

A spontaneous rough (Rg) mutant of M. avium ATCC 15769 was mutagenized using N-methyl-N-nitro-nitrosoguanidine (MNNG). Out of 54 clones initially chosen on the basis of their morphological appearance on the 7H11 agar, seven Rg clones were selected on the basis of their response to current biochemical tests, and were later characterized for their cell wall amphiphilic contents (analysis of loosely-bound surface lipids for mycosides, peptidolipids, phospholipids, and mycolic acids by thin layer chromatography, and fatty acids by gas chromatography), and ability to grow intracellularly inside J-774 macrophages. A parallel study was also performed on a previously reported Rg mutant of M. intracellulare serovar 20 (W.W. Barrow and P.J. Brennan, J. Bact. 150 (1982) 381-384) which lacked the ability to synthesize mycosides C (MYC-). The results obtained were compared to parental smooth (Sm) colony-types of the respective M. avium-intracellulare strains. Our results showed that neither the ninhydrin-reacting lipids (probably peptidolipids) nor the glycopeptidolipids (mycosides C) were primary factors responsible for the intracellular survival and multiplication of these bacteria. Ultrastructural studies showed that although the polysaccharide-rich outer wall layer (POL) in case of MYC- Rg strain was not uniformly distributed and contained blebs, these bacteria formed the characteristic electron-transparent zone (ETZ) upon phagocytes by macrophages. Furthermore, the multiplication of MYC- Rg strain inside macrophages did not result in intracellular selection of MYC+ bacteria, nor in Rg to Sm transition.

Cell Line↗
PubMed1989

Human IgG antibodies immunoreacting with specific sulfolipids from Mycobacterium tuberculosis.

IgG and IgM antibodies immunoreacting with sulfolipids from Mycobacterium tuberculosis were detected in sera from tuberculosis patients. The method used was an enzyme linked immunoassay (ELISA) and the antigens were a 2, 3, 6, 6' tetraacyl trehalose-2'-sulfate (sulfolipid I, SL I) and a 2, 3 diacyl trehalose-2'-sulfate (sulfolipid IV, SL IV). The SL IV antigen was satisfactory for IgG assays. The sensitivity and the specificity of the test were, respectively, 59 and 100%; the predictive values of a positive and negative test were, respectively, 100 and 76%.

Antibodies, Bacterial↗
PubMed1989

Glycolipids of recent clinical isolates of Mycobacterium tuberculosis: chemical characterization and immunoreactivity.

Five distinct glycolipids were readily detected in isolates of Mycobacterium tuberculosis. Spectroscopic methods and chemical degradation techniques allowed the structural identification of four of these glycolipids. The specific phenolic glycolipid antigen previously characterized from the Canetti strain was found in all the strains examined, with identical structural features (triglycosyl phenol phthiocerol dimycocerosate). The other three glycolipids identified were acylated trehaloses: penta-acyl trehalose (containing phthienoyl substituents), tetra-acyl trehalose 2'-sulphate (with C40-C50 hydroxyphthioceranoyl substituents) and diacyl trehalose 2'-sulphate (with C16 and C18 substituents). The two latter glycolipids as well as the phenolic glycolipid immunoreacted with whole-cell antiserum, indicating their surface location. The occurrence of these glycolipid antigens in recent clinical isolates suggests their possible utilization in the serodiagnosis of tuberculosis and the rapid identification of M. tuberculosis with specific antisera.

Chromatography, Thin Layer↗
PubMed1989

Non-cultivable mycobacteria in ulcers of the skin.

In biopsies of 54 patients suffering from chronic dermatological lesions (mostly ulcers of the skin) acid-fast bacilli were found in 14. In these 14 cases in 4 were lesions caused by M. tuberculosis, in 1 the lesion was caused by M. avium-intracellulare, in 1 the lesion was caused by M. fortuitum and in 2 the lesions were caused by non-cultivable mycobacteria (Feldmann-Hershfield ulcer?). In 2 cases the cultures were heavily contaminated, and the diagnosis remained uncertain. In the remaining 4 cases the mycobacteria were considered occasional isolates without clinical significance.

Adolescent↗
PubMed1989

Immunological response to homologous and heterologous phenolic glycolipid antigens in tuberculosis and leprosy.

The occurrence of IgM antibodies immunoreacting in an ELISA test with five phenolic-glycolipids (GPL) antigens (PGL-Tb 1, from M. tuberculosis; PGL-I, from M. leprae; PGK-K-I, from M. kansasii; Mycoside G, from M. marinum; and Mycoside B, from M. bovis), was examined in the sera of 46 tuberculous patients, 48 multibacillary leprosy patients, 40 paucibacillary leprosy patients and in 134 healthy controls. The sensitivity (97.9) and the specificity (91.8) observed in tuberculous patients with the homologous antigen PGL-Tb 1 underlined the interest of this antigen for case finding in tuberculosis epidemiology. The sensitivity and the specificity observed in multibacillary leprosy patients, respectively 91.7 and 91.8, and in paucibacillary leprosy patients, respectively, 35.0 and 91.7, confirmed the limited value of homologous antigen PGL-I for the serological case finding of leprosy patients in endemic areas with a strong incidence of paucibacillary leprosy forms. The data obtained with the heterologous PGL antigens in tuberculosis and multibacillary leprosy serology were higher than those observed in healthy controls and in paucibacillary leprosy patients. However the ELISA using the heterologous antigens was not useful in diagnosis of active tuberculosis or multibacillary leprosy forms. Healthy controls showed low immunoreactivity against PGL antigens, with the exception of mycoside B.

Adolescent↗
PubMed1989

Comparative intracellular growth of difficult-to-grow and other mycobacteria in a macrophage cell line.

We have recently developed a murine macrophage cell line (J-774) model which permits the growth of various mycobacteria (8). The purpose of the present investigation was to compare the intracellular growth of various difficult-to-grow mycobacteria (Mycobacterium paratuberculosis, M. ulcerans), and other pathogenic (M. tuberculosis H37Rv, M. kansasii, M. bovis) and nonpathogenic or avirulent (M. tuberculosis H37Ra, M. bovis BCG, M. gastri) mycobacteria. Electron microscopic studies were also performed to elucidate whether the formation of an electron-transparent zone (ETZ) around phagocytized bacilli was linked to their intramacrophagic survival. Furthermore, the comparison of intracellular growth of a pathogenic (M. kansasii) and nonpathogenic (M. gastri) mycobacteria sharing the same phenolic glycolipid antigen at their surface (Mycoside-A, 5), suggested that these antigens did not play a primary role in intracellular survival and multiplication of these bacteria. Also, we were unable to propagate M. ulcerans inside J-774 macrophages, which were massively lyzed after infection (due to a characteristic toxin secreted inside the macrophages?). These results are discussed in terms of the validity of the J-774 model for studying intracellular growth of mycobacteria.

Animals↗
PubMed1989

Restriction map of mycobacteriophage D29 and its deletion mutant F5.

A physical map of mycobacteriophage D29 was constructed, including positions for 25 restriction sites for 9 endunocleasic enzymes. D29 DNA contains about 48 150 bp. Analysis of a deletion mutant (F5) has allowed to determine the location of two non essential regions in the genome, allowing further insertion of foreign genes and construction of cosmids.

Chromosome Deletion↗
PubMed1989

Serologic and immunocytochemical analysis of the Mycobacterium avium cell envelope.

Whole cell sonicates of Mycobacterium avium ATCC 15769, and subcellular fractions (CYT, cytosol; CM, cytoplasmic membrane; CWS, delipidated cell wall skeleton; OL, native lipids; and SDS, sodium dodecylsulfate extract of whole cells) were injected into rabbits to produce corresponding antisera. Immunoelectrophoretic analysis and immunochemical observations using electron microscopy showed that few of the antigens synthetized intracellularly were exported and located in the bacterial outer layers, and that the outer layers contained wall specific antigens possibly in situ assembled.

Antibodies, Bacterial↗
PubMed1989

Methionine as methyl-group donor in the synthesis of Mycobacterium avium envelope lipids, and its inhibition by DL-ethionine, D-norleucine and DL-norleucine.

The radioactivity from 3H-methyl methionine was rapidly incorporated into the surface lipids of Mycobacterium avium. The transmethylation reaction was efficiently inhibited by DL-ethionine, D-norleucine and DL-norleucine. The structure of the outerlayer of the M. avium envelope was profoundly altered in the bacteria treated with DL-norleucine.

Cell Wall↗