Search PubMed⌕ Search

Biomedical subjects

J J McFadden

Publications and source records attributed to J J McFadden.

At least 19 recordsLinked to original sources
PubMed1998

IS990, a new species-specific insertion-sequence-related element of the Mycobacterium tuberculosis complex.

The structure and distribution of 1S990, a new Mycobacterium tuberculosis DNA sequence with homology to characterized insertion sequences (ISs), were investigated. IS990 was related to IS elements of the IS3 family and was present as a single copy in all 21 investigated M. tuberculosis strains, two Mycobacterium bovis strains and two M. bovis BCG strains. The sequence appears to be specific for the M. tuberculosis complex. The element carries two frameshift mutations and appears to be defective.

Amino Acid Sequence↗
PubMed1997

Characterization of Mycobacterium avium complex related mycobacteria isolated from an African environment and patients with AIDS.

Thirteen isolates from African AIDS patients and from the environment in Zaire were identified as members of the Mycobacterium avium complex by phenotypic tests. RFLP analysis showed that the isolates belong to a genetically homogeneous cluster. The 16S rRNA sequence analysis suggests a close relationship with the P-49 strain (ATCC 35847), a reference strain for the serotype 7 of M. avium complex. This work shows the close relationship between certain M. avium complex strains responsible for disseminated infection in AIDS patients and M. avium complex strains isolated from the environment in Zaire. Further, our findings confirm that atypical mycobacteria may disseminate in AIDS patients in Africa and suggest that infection in these patients probably originates in their environment.

AIDS-Related Opportunistic Infections↗
PubMed1994

Specific detection of Mycobacterium paratuberculosis DNA associated with granulomatous tissue in Crohn's disease.

The role of mycobacteria, specifically Mycobacterium paratuberculosis, in Crohn's disease has aroused considerable controversy for many years. Using the ultra sensitive polymerase chain reaction some studies have reported detection of M paratuberculosis DNA in as many as 65% of Crohn's disease patients but also in patients without disease. Other studies have been negative for both groups. We therefore designed a double blind control trial to investigate the presence of mycobacterial DNA in age, sex, and tissue matched paraffin wax embedded tissues from 31 Crohn's disease tissues, 20 diseased gut control tissues, and 10 ulcerative colitis tissues. The specimens were coded and analysed blind with three separate polymerase chain reactions (PCR) based on DNA sequences specific for M paratuberculosis (IS900), M avium (RFLP type A/1) (IS901), and the Mycobacterium genus (65 kDa gene, TB600). The number of granulomata and presence of acid fast bacilli in each Crohn's disease tissue was also investigated. The sensitivity of the system was determined using similarly prepared gut tissue from an animal infected with M paratuberculosis. Four of 31 Crohn's disease tissues and none of the 30 control and ulcerative colitis derived tissues amplified M paratuberculosis DNA. Crohn's disease tissues containing granulomata were significantly more likely to amplify M paratuberculosis specific DNA on PCR than the non-Crohn's disease tissues (p = 0.02). All the positive Crohn's disease tissues contained granulomata, and none contained acid fast bacilli. Equivalent numbers of Crohn's and non-Crohn's disease tissues amplified the region of the 65 kD gene on PCR for non-specific mycobacterial DNA (11/31 and 9/30 respectively). No sections produced an amplified product with the IS901 PCR. These results suggest that few Crohn's disease gut biopsy sections contain M paratuberculosis DNA in association with granulomata. The absence of such DNA in any control and ulcerative colitic tissue strengthens the case for it having a specific association, which may be pathogenic, with Crohn's disease in this minority of patients.

Adult↗
PubMed1993

Identification of spheroplast-like agents isolated from tissues of patients with Crohn's disease and control tissues by polymerase chain reaction.

Mycobacterium paratuberculosis has been isolated from tissue taken from patients with Crohn's disease and has been implicated in the etiology of this disease. On culture, the organisms appear initially as cell wall-deficient, spheroplast-like forms that are difficult to identify by conventional techniques. Here we examine 30 unidentified cultures by the polymerase chain reaction using primers specific for M. paratuberculosis, Mycobacterium tuberculosis, and Mycobacterium avium restriction fragment length polymorphism type A/I and also by a non-species-specific mycobacterial polymerase chain reaction. Six of these cultures, all from Crohn's disease, were shown to contain DNA from M. paratuberculosis. Cultures from both Crohn's disease and controls were found to contain mycobacterial DNA of unknown specific origin.

Base Sequence↗
PubMed1992

Phylogenetic and epidemiological analysis of Neisseria meningitidis using DNA probes.

The genetic relationships between various serotypes and serogroups of meningococcal strains were investigated by restriction fragment-length polymorphism (RFLP) analysis using a number of random DNA probes and a probe containing a truncated copy of the meningococcal insertion sequence IS1106. The data were used to estimate genetic distance between all pairs of strains and to construct phylogenetic trees for meningococcal strains. B15:P1.16R strains isolated from cases of systemic meningococcal disease in two health districts with a high incidence of disease were clonal in contrast to similar strains from cases occurring in other parts of the UK. Strains from these areas, which contain a similar genomic deletion, were found to be derived from two distinct lineages within the B15:P1.16R phylogenetic group. RFLP data demonstrated that present serological typing systems for the meningococcus do not necessarily reflect true genetic relationships.

Blotting, Southern↗
PubMed1992

Identification and characterization of a novel insertion sequence, IS1106, downstream of the porA gene in B15 Neisseria meningitidis.

Examination of Neisseria meningitidis strains associated with endemic meningococcal disease demonstrated differences in the number of copies of a repetitive sequence. Characterization of a copy of this repetitive sequence present in B15 strains has revealed the presence of a novel insertion sequence (IS1106) located within a complex repetitive region downstream of the gene for the major surface antigen (porA). IS1106 has a length of 1137 bp and is flanked by 36bp inverted repeats. Two open reading frames (ORF1 and ORF2) are present in opposite strands in codon-codon register with ORF2 entirely located within ORF1. The predicted protein from ORF1 demonstrates homology with the 5A protein of IS5 (Kroger and Hobom, 1982). Strains from two independent outbreaks of B15 meningococcal disease in the UK were found to contain the same genomic deletion removing a copy of IS1106 downstream of the porA gene.

Alleles↗
PubMed1992

Biologically distinct subtypes of Mycobacterium avium differ in possession of insertion sequence IS901.

Mycobacterium avium causes disease, principally tuberculosis in immunocompromised individuals. It is the most frequent cause of disseminated infections in AIDS patients in the West. The pathogen is also associated with disease in animals, chiefly birds and livestock, and may be isolated from environmental samples such as soil and water. Analysis of strains of M. avium isolated from clinical, veterinary, and environmental sources for the presence of the mycobacterial insertion sequences IS900 and IS901 demonstrates the specific association of IS901 to animal pathogenic M. avium strains. In contrast, most clinical M. avium strains and all AIDS-derived strains examined so far lacked IS901. Significant differences in the plasmid contents and serotypes of strains with and without IS901 were also found. We therefore suggest that the presence of IS901 divides M. avium into two clearly distinct subtypes with differing host range, virulence, plasmid possession, and serotyping antigens. By using DNA sequence data from IS901 and M. avium DNA, a set of polymerase chain reactions were developed for the specific detection and differentiation of these subtypes.

Animals↗
PubMed1991

IS901, a new member of a widespread class of atypical insertion sequences, is associated with pathogenicity in Mycobacterium avium.

An insertion sequence (IS901), found in pathogenic strains of Mycobacterium avium, but absent in M. avium complex isolates from patients with acquired immune deficiency syndrome (AIDS), has been isolated and sequenced. This insertion element has a nucleotide sequence of 1472 bp, with one open reading frame (ORF1), which codes for a protein of 401 amino acids. The amino acid sequence, terminal ends and target site of IS901 are similar to those of IS900, present in Mycobacterium paratuberculosis. However, the DNA sequences of these two IS elements exhibit only 60% homology, compared to a DNA homology of 98% between their respective hosts. IS901, like IS900, appears to belong to a family of related insertion elements present in actinomycetes and other bacteria. M. avium strains containing IS901 were found to be more virulent in mice than closely related strains lacking IS901. IS901 may be a useful tool for the study of the genetics of virulence in the M. avium complex and for obtaining stable integration of foreign genes into mycobacteria.

Acquired Immunodeficiency Syndrome↗
PubMed1990

In vitro hydroxylation of bentazon by microsomes from naphthalic anhydride-treated corn shoots.

In vitro metabolism of the herbicide bentazon was studied in microsomal membranes isolated from 6-day-old etiolated corn shoots. Microsomes isolated from shoots of nontreated seeds did not metabolize bentazon when assayed with NADPH or peroxides. However, microsomes isolated from shoots of seeds pretreated with naphthalic anhydride formed a single bentazon metabolite when provided with NADPH. The metabolite was identified as 6-hydroxybentazon, the major phase I metabolite produced in vivo. In vitro formation of this metabolite was strongly inhibited by carbon monoxide, nitrogen, and tetcyclacis (10 microM). The results suggest that aryl hydroxylation of bentazon in corn shoots is catalyzed by a cytochrome P-450 (E.C. 1.14.14.1) and that a seed pretreatment with naphthalic anhydride is necessary for recovery of activity in vitro.

Benzothiadiazines↗
PubMed1990

Use of highly specific DNA probes and the polymerase chain reaction to detect Mycobacterium paratuberculosis in Johne's disease.

DNA probes that hybridize to a mycobacterial insertion sequence, IS900, present in multiple copies in the genome of Mycobacterium paratuberculosis were found to be highly specific for M. paratuberculosis. DNA sequences derived from IS900 were used to prepare DNA primers for detection and identification of M. paratuberculosis by the polymerase chain reaction. Highly specific direct detection of M. paratuberculosis DNA in feces from cattle with Johne's disease was obtained. The polymerase chain reaction test had a sensitivity equal to or greater than that obtained by standard culture techniques and was much more rapid, taking only hours compared with 6 to 12 weeks for culture.

Animals↗
PubMed1989

Sequence and characteristics of IS900, an insertion element identified in a human Crohn's disease isolate of Mycobacterium paratuberculosis.

The complete sequence of an insertion element IS900 in Mycobacterium paratuberculosis is reported. This is the first characterised example of a mycobacterial insertion element. IS900 consists of 1451bp of which 66% is G + C. It lacks terminal inverted and direct repeats, characteristic of Escherichia coli insertion elements but shows a degree of target sequence specificity. A single open reading frame (ORF 1197) coding for 399 amino acids is predicted. This amino acid sequence, and to a lesser extent the nucleotide sequence, show significant homologies to IS110, an insertion element of Streptomyces coelicolor A3(2). It is proposed that IS900, IS110, and similar insertion elements recently identified in disease isolates of Mycobacterium avium are members of a phylogenetically related family. IS900 will provide highly specific markers for the precise identification of Mycobacterium paratuberculosis, useful in defining its relationship to animal and human diseases.

Amino Acid Sequence↗
PubMed1989

DNA probes demonstrate a single highly conserved strain of Mycobacterium avium infecting AIDS patients.

Strains of the Mycobacterium avium intracellulare complex (MAIC) have become important colonisers of patients with acquired immunodeficiency syndrome (AIDS). Restriction fragment length polymorphisms were used to study the DNA from 88 MAIC isolates, including 51 derived from 47 AIDS patients. MAIC isolates from 33 of 45 AIDS patients were identical at the molecular level and distinct from the mycobacteria isolated from the stools of healthy subjects. The study also showed that serotyping correlates poorly with the genetic identity of these organisms. Mycobacterium paratuberculosis, which has been implicated in Crohn's disease, was not identified in any of the cultures studied.

Acquired Immunodeficiency Syndrome↗