Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0026918 (Mycobacterium)
 52,428 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Infectious diseases and malnutrition represent major burdens afflicting millions of people in developing countries. Both conditions affect individuals in industrialized nations, particularly the aged, the HIV-infected, and people with chronic diseases. While malnutrition is known to induce a state of immunodeficiency, the mechanisms responsible for compromised antimicrobial resistance in malnourished hosts remain obscure. In the present study, mice fed a 2% protein diet and developing protein calorie malnutrition, in contrast to well-nourished controls receiving a 20% protein diet, rapidly succumbed to infection with Mycobacterium tuberculosis. Malnourished mice exhibited a tissue-specific diminution in the expression of interferon gamma, tumor necrosis factor alpha, and the inducible form of nitric oxide synthase in the lungs, but not the liver. The expression of these molecules critical to the production of mycobactericidal nitrogen oxides was depressed in malnourished animals in the lungs specifically at early times (< 14 days) after infection. At later times, levels of expression became comparable to those in well-nourished controls, although the bacillary burden in the malnourished animals continued to rise. Nevertheless, urinary and serum nitrate contents, an index of total nitric oxide (NO) production in vivo, were not detectably diminished in malnourished, mycobacteria-infected mice. In contrast to the selective and early reduction of lymphokines and the inducible form of nitric oxide synthase in the lung, a marked diminution of the granulomatous reaction was observed in malnourished mice throughout the entire course of infection in all tissues examined (lungs, liver, and spleen). Remarkably, the progressively fatal course of tuberculosis observed in the malnourished mice could be reversed by restoring a full protein (20%) diet. The results indicate that protein calorie malnutrition selectively compromises several components of the cellular immune response that are important for containing and restricting tuberculous infection, and suggest that malnutrition-induced susceptibility to some infectious diseases can be reversed or ameliorated by nutritional intervention.
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PMID:Effects of protein calorie malnutrition on tuberculosis in mice. 896 45

A 54-year-old woman with pulmonary tuberculosis developed pneumonia caused by Scedosporium apiospermum, the asexual stage of the fungus Pseudallescheria boydii. Mycobacterium tuberculosis and P boydii were cultured in BAL fluid. The patient cleaned swimming pools in a spa health resort and was highly exposed to fungal conidia. She was successfully treated with antituberculosis drugs, miconazole nitrate and ketoconazole, leading to remission of her pulmonary infection. Invasive pulmonary pseudallescheriasis associated with tuberculosis is an unusual finding, especially in an immunocompetent individual.
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PMID:Pulmonary tuberculosis associated with invasive pseudallescheriasis. 904 7

We prepared a Nocardia brasiliensis cell extract and purified two immunodominant antigens with molecular weights of 61,000 and 24,000. The isolated proteins were shown to be reasonably pure when analyzed with sodium dodecyl sulfate-polyacrylamide gel electrophoresis (8 to 18% polyacrylamide gradient) and stained with Coomassie blue and silver nitrate. By using an immunoelectrotransfer blot method (Western blotting), we demonstrated that these two purified proteins reacted strongly with serum from N. brasiliensis-infected mycetoma patients. To obtain anti-P61 and anti-P24 monoclonal antibodies (MAbs), we used an N. brasiliensis cell extract as the antigen for the first immunization; 2 weeks later female mice were reimmunized with a semipurified antigen containing the P24 or P61 fraction. A booster injection was given 3 days before the fusion was carried out. Two hybrids that reacted strongly with P24 were cloned by limiting dilution, the generated MAbs were analyzed for isotyping, and their specificity was tested in a Western blot assay with cell extracts from Nocardia asteroides and Mycobacterium tuberculosis cultures. Anti-P24 MAbs were shown to be specific for N. brasiliensis HUJEG-1 and did not cross-react with either the N. asteroides or M. tuberculosis strains used. However, additional studies with several N. asteroides and N. brasiliensis strains are needed to investigate whether there are cross-reactions between strains or species when these MAbs are used. The anti-P61 and anti-24 MAbs were used to locate the antigen in N. brasiliensis cells by immunofluorescence. The lack of reaction with intact cells suggests that the P24 and P61 antigens are not exposed in the complete bacterial cell surface or that the recognized epitopes are different. Only one anti-P61 MAb that reacted specifically with the N. brasiliensis cell extract was obtained.
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PMID:Monoclonal antibodies to P24 and P61 immunodominant antigens from Nocardia brasiliensis. 906 45

Apolipoprotein E (apoE) is a constituent of lipoproteins other than low-density lipoprotein, and it principally acts in the transport and metabolism of plasma cholesterol and triglyceride. ApoE is a minor constituent of various kinds of amyloidoses and may play a role as a pathological chaperone for fibrillogenesis of amyloid fibril protein with the amyloid P component and proteoglycans. In this study, we examined the role of apoE in amyloidogenesis in vivo in apoE-deficient mutant mice with amyloid A protein (AA) amyloidosis induced by inflammatory stimulation. Amyloid deposition was seen in six of nine C57BL/6J control mice and in six of eight apoE-deficient mutant mice after the intraperitoneal and subcutaneous injections of the mixture of complete Freund's adjuvant and Mycobacterium butyricum. Moreover, amyloid deposition in apoE-deficient mice as well as C57BL/6J control mice started 48 or 72 hours after injection of amyloid-enhancing factor and silver nitrate, although the amount of amyloid deposit in C57BL/6J control mice was slightly larger than that in apoE-deficient mice. These amyloid deposits reacted with anti-mouse AA antibody were seen in the perifollicular area of the spleen. Immunoreactivity of apoE was seen irregularly in the amyloid deposits of C57BL/6J control mice but not in the amyloid deposit of apoE-deficient mice. From these results, we concluded that apoE is not always necessary for amyloid deposition and that the existence of apoE might slightly accelerate AA amyloid deposition in the earliest phase of AA amyloid deposition.
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PMID:Amyloid A protein amyloidosis induced in apolipoprotein-E-deficient mice. 932 23

Isolates from the Mycobacterium tuberculosis complex cultured from caprine pathological tissue samples were biochemically and genetically characterized. The isolates were negative for nitrate reduction and niacin accumulation, they weakly hydrolysed Tween 80, were sensitive to pyrazinamide (50 micrograms ml-1) and were resistant to 1 and 2 micrograms tiophene-2-carboxylic acid hydrazide ml-1 but not to 5 or 10 micrograms tiophene-2-carboxylic acid hydrazide ml-1. Sequencing of the pncA gene revealed a polymorphism characteristic of M. tuberculosis, whereas oxyR, katG and gyrA sequences were characteristic of Mycobacterium bovis. The fingerprinting patterns obtained with IS6110, direct repeats and polymorphic G+C-rich sequence-associated RFLP and direct variable repeat-spacer oligonucelotide typing (spoligotyping) segregated these isolates from the other members of the complex. The results of this testing, together with the repeated association of this micro-organism with goats, suggest that a new member of this taxonomic complex not matching any of the classical species had been identified. This unusual mycobacterium may play a role in the epidemiology of animal and human tuberculosis in Spain. The name Mycobacterium tuberculosis subsp. caprae subsp. nov. is proposed for these isolates. The type strain of Mycobacterium tuberculosis subsp. caprae subsp. nov. is gM-1T (= CIP 105776T).
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PMID:Mycobacterium tuberculosis subsp. caprae subsp. nov.: a taxonomic study of a new member of the Mycobacterium tuberculosis complex isolated from goats in Spain. 1042 90

Granuloma formation in response to mycobacterial infections is associated with increased expression of inducible nitric oxide synthase (NOS2) within granuloma macrophages and increased levels of nitrate/nitrite in the sera of infected mice. Continuous treatment with 5 mm or 10 mm l-N6-(1-imino-ethyl)-lysine (L-NIL), a selective NOS2-inhibitor, in acidified drinking water for up to 7 weeks consistently reduced infection-induced nitrate/nitrite to background levels in mycobacteria-infected BALB/c mice. Oral treatment with 5 mm L-NIL initiated at the time of infection significantly exacerbated growth of Mycobacterium tuberculosis, but had no effect on Mycobacterium avium colony-forming unit development in the liver, spleen and lungs of intravenously infected mice. In order to examine the role of nitric oxide in mycobacteria-induced granulomatous inflammation in the absence of any effect on the bacterial load, M. avium-infected mice were treated with 5 mm L-NIL from day 1 through 38 and the development of granulomatous lesions in the liver was assessed by histology, immunohistology and reverse-transcription-polymerase chain reaction (RT-PCR). Computer- and video-assisted morphometry performed at 4 and 7 weeks post-infection showed that treatment with L-NIL led to markedly increased number, cellularity and size of granulomatous lesions in infected mice regardless of the virulence of the M. avium isolate used for infection. Immunohistology of the liver revealed that in mice treated with L-NIL, the numbers of CD3+ T cells, CD21/35+ B cells, CD11b+ macrophages and RB6-8C5+ granulocytes associated with granulomatous lesions was increased. RT-PCR of the liver showed that in L-NIL-treated mice infected with M. avium, mRNA levels of tumour necrosis factor, interleukin-12p40, interferon-gamma, interleukin-10 and interferon-gamma-inducible protein-10 (IP-10) were up-regulated, while mRNA levels of interleukin-4, monocyte chemotactic protein-1 (MCP-1) and MCP-5 were similar to those in untreated control infected mice. When M. avium-infected mice were treated with 5 mm L-NIL between the 5th and 12th weeks of infection, similar changes in granuloma number and size were found in the absence of any effect on the bacterial load. These findings demonstrate that nitric oxide regulates the number, size and cellular composition of M. avium-induced granulomas independently of antibacterial effects by modulating the cytokine profile within infected tissues.
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PMID:NOS2-derived nitric oxide regulates the size, quantity and quality of granuloma formation in Mycobacterium avium-infected mice without affecting bacterial loads. 1058 88

Mycobacterium tuberculosis and Mycobacterium bovis cause tuberculosis, which is responsible for the deaths of more people each year than any other bacterial infectious disease. Disseminated disease with Mycobacterium bovis BCG, the only currently available vaccine against tuberculosis, occurs in immunocompetent and immunodeficient individuals. Although mycobacteria are obligate aerobes, they are thought to face an anaerobic environment during infection, notably inside abscesses and granulomas. The purpose of this study was to define a metabolic pathway that could allow mycobacteria to exist under these conditions. Recently, the complete genome of M. tuberculosis has been sequenced, and genes homologous to an anaerobic nitrate reductase (narGHJI), an enzyme allowing nitrate respiration when oxygen is absent, were found. Here, we show that the narGHJI cluster of M. tuberculosis is functional as it conferred anaerobic nitrate reductase activity to Mycobacterium smegmatis. A narG mutant of M. bovis BCG was generated by targeted gene deletion. The mutant lacked the ability to reduce nitrate under anaerobic conditions. Both mutant and M. bovis BCG wild type grew equally well under aerobic conditions in vitro. Histology of immunodeficient mice (SCID) infected with M. bovis BCG wild type revealed large granulomas teeming with acid-fast bacilli; all mice showed signs of clinical disease after 50 days and succumbed after 80 days. In contrast, mice infected with the mutant had smaller granulomas containing fewer bacteria; these mice showed no signs of clinical disease after more than 200 days. Thus, it seems that nitrate respiration contributes significantly to virulence of M. bovis BCG in immunodeficient SCID mice.
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PMID:Anaerobic nitrate reductase (narGHJI) activity of Mycobacterium bovis BCG in vitro and its contribution to virulence in immunodeficient mice. 1071 84

Nitric oxide (NO) is present in soil and air, and is produced by bacteria, animals and plants. Superoxide (O2-) arises in all organisms inhabiting aerobic environments. Thus, many organisms are likely to encounter peroxynitrite (OONO-), a product of NO and O2- that forms at near diffusion-limited rates, and rapidly decomposes upon protonation through isomerization to nitrate (NO3-; ref. 1) while generating hydroxyl radical (*OH) and nitrogen dioxide radical (*NO2) (refs 2, 3), both more reactive than peroxynitrite's precursors. The oxidative, inflammatory, mutagenic and cytotoxic potential (ref. 4) of peroxynitrite contrasts with the antioxidant, anti-inflammatory and tissue-protective properties ascribed to NO itself. Thus, the ability of cells to cope with peroxynitrite is central in determining the biological consequences of NO production. We considered whether cells might be equipped with enzymes to detoxify peroxynitrite. Peroxiredoxins have been identified in most genomes sequenced, but their functions are only partly understood. Here we show that the peroxiredoxin alkylhydroperoxide reductase subunit C (AhpC) from Salmonella typhimurium catalytically detoxifies peroxynitrite to nitrite fast enough to forestall the oxidation of bystander molecules such as DNA. Results are similar with peroxiredoxins from Mycobacterium tuberculosis and Helicobacter pylori. Thus, peroxynitrite reductase activity may be widespread among bacterial genera.
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PMID:Peroxynitrite reductase activity of bacterial peroxiredoxins. 1100 Oct 62

Investigation into recent declines in striped bass health in the Chesapeake Bay in Maryland resulted in the isolation of a putative new species of Mycobacterium. This isolate was obtained from fish showing skin ulcers and internal granulomas in various organs. The isolate was slow growing at 28 degrees C; was nonchromogenic; showed no activities of nitrate reduction, catalase activity, Tween 80 hydrolysis, tellurite reduction, or arylsulfatase reduction; grew best at low salt concentrations; and was urease and pyrazinamidase positive. By PCR a unique insertional sequence was identified which matched nothing in any database. Analysis of the nearly complete 16S rRNA gene sequence also indicated a unique sequence which had 87.7% sequence homology to Mycobacterium ulcerans, 87.6% homology to Mycobacterium tuberculosis, and 85.9% homology to Mycobacterium marinum. Phylogenetic analysis placed the organism close to the tuberculosis complex. These data support the conclusion that the isolate probably represents a new mycobacterial species.
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PMID:Detection of a new Mycobacterium species in wild striped bass in the Chesapeake Bay. 1115 32

Mycobacterium bovis BCG, the only presently available vaccine against tuberculosis, was obtained from virulent M. bovis after serial passages in vitro. The vaccine strain retained at least some of its original virulence, as it persists in immune-competent hosts and occasionally may cause fatal disease in immune-deficient hosts. Mycobacterial persistence in vivo is thought to depend on anaerobic metabolism, an apparent paradox since all mycobacteria are obligate aerobes. Here we report that M. bovis BCG lacking anaerobic nitrate reductase (NarGHJI), an enzyme essential for nitrate respiration, failed to persist in the lungs, liver, and kidneys of immune-competent (BALB/c) mice. In immune-deficient (SCID) mice, however, bacilli caused chronic infection despite disruption of narG, even if growth of the mutant was severely impaired in lungs, liver, and kidneys. Persistence and growth of BCG in the spleens of either mouse strain appeared largely unaffected by lack of anaerobic nitrate reductase, indicating that the role of the enzyme in pathogenesis is tissue specific. These data suggest first that anaerobic nitrate reduction is essential for metabolism of M. bovis BCG in immune-competent but not immune-deficient mice and second that its role in mycobacterial disease is tissue specific, both of which are observations with important implications for pathogenesis of mycobacteria and vaccine development.
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PMID:Dependence of Mycobacterium bovis BCG on anaerobic nitrate reductase for persistence is tissue specific. 1174 94


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