[Rifabutin. An antibiotic against mycobacteria].
Explore the source record for details and available documents.
AIDS-Related Opportunistic Infections↗
Biomedical subjects
A B Andersen
Publications and source records attributed to A B Andersen.
[Drug handling--quality assurance of routines].
Explore the source record for details and available documents.
Community Health Nursing↗
Mannan-binding lectin in the sub-Saharan HIV and tuberculosis epidemics.
Inherited deficiency of mannan-binding lectin (MBL) has been shown to predispose to infections. Conversely, it has also been suggested that MBL might facilitate the uptake of certain intracellular microbes. The aim of this study was to investigate whether MBL plays a role in the HIV and tuberculosis epidemics in Africa. Thus, the authors determined the MBL serum concentration in 173 HIV infected patients (150 with concomitant tuberculosis), 94 patients with tuberculosis without being HIV infected, and 113 controls from Tanzania. The frequency of MBL deficiency was significantly increased in HIV infected patients compared with controls (12.1% and 3.5%, respectively). The frequency of patients deficient of MBL did not differ between controls and HIV negative patients with tuberculosis. However, HIV negative patients with tuberculosis had significantly higher MBL levels than both controls and HIV infected patients with or without tuberculosis. These results indicate that low levels of MBL are associated with increased risk of sexually transmitted HIV infection in Africans. By contrast, high levels of MBL may be involved in the pathogenesis of tuberculosis in immunocompetent individuals.
Adolescent↗
False-positive results from cultures of Mycobacterium tuberculosis due to laboratory cross-contamination confirmed by restriction fragment length polymorphism.
During 1994, a cross-contamination problem leading to false-positive cultures of Mycobacterium tuberculosis was revealed in a mycobacteriology laboratory processing 30,000 to 35,000 samples per year. Molecular strain typing based on restriction fragment length polymorphism confirmed the contaminations. Out of 1,439 positive cultures of Mycobacterium tuberculosis, 49 samples from 48 patients were suspected to be cross-contaminated. In 37 cases, growth was observed both in BACTEC vials and on solid media, indicating that the contamination took place during the processing of the samples. The majority of the contaminated samples had been handled by the same technician.
Bacterial Typing Techniques↗
Occurrence of otitis media in an arctic region.
The occurrence of otitis media (OM) was examined retrospectively in files at Longyearbyen Hospital, Svalbard, Norway during 1991-1994. Acute OM (AOM) with and without spontaneous drum perforation, secretory OM (SOM) and chronic OM (COM) with and without suppuration were registered, as were patient's sex, age, and climatic conditions. These findings were compared with weather observations obtained from the Norwegian Meteorological Institute, Tromsø in the same period. Sixty-four percent of the OM patients registered were classified as AOM, 17% having a spontaneous drum perforation. Thirty percent suffered from SOM, whereas 6% had COM. Forty percent of the patients were younger than 6 years. The distribution of OM cases during the year showed a peak during the spring, especially in May. Another minor peak was noted in September. Average daily temperature in the period was -5.6 degrees C, range -14 degrees C to +6 degrees C. Humidity and precipitation were fairly stable throughout the observation period 74% and 240 mm/year, respectively. OM is a common disease at Svalbard and is apparently related to seasonal shifts in temperature.
Acute Disease↗
A Mycobacterium tuberculosis gene cluster encoding proteins of a phosphate transporter homologous to the Escherichia coli Pst system.
We report the cloning and sequencing of three M. tuberculosis genes encoding proteins homologous to E. coli PstA, PstC and PstB. They are tentatively called pstA-2, pstC-1 and pstB. They encode proteins of 302, 336 and 275 amino acids, respectively. In E. coli, PstB is the ATP binding component and PstA/PstC are the two hydrophobic subunits of a phosphate permease belonging to the family of ABC (ATP-binding cassette) transporters. In mycobacteria, PstS-1, the phosphate binding subunit (Andersen and Hansen, 1989), is encoded by a gene directly surrounded by pstB, pstC-1 and pstA-2 within a potential operon (pstB, pstS-1, pstC-1, pstA-2). Phosphate uptake by whole, suspension grown, M. bovis BCG cells was measured and could be inhibited by a monoclonal antibody directed against the PstS-1 subunit, suggesting that these genes encode subunits of a functional mycobacterial phosphate permease.
ATP-Binding Cassette Transporters↗
Key epitopes on the ESAT-6 antigen recognized in mice during the recall of protective immunity to Mycobacterium tuberculosis.
The recall of long-lived immunity in a mouse model of tuberculosis (TB) is defined as an accelerated accumulation of reactive T cells in the target organs. We have recently identified Ag 85B and a 6-kilodalton early secretory antigenic target, designated ESAT-6, as key antigenic targets recognized by these cells. In the present study, preferential recognition of the ESAT-6 Ag during the recall of immunity was found to be shared by five of six genetically different strains of mice. Overlapping peptides spanning the sequence of ESAT-6 were used to map two T cell epitopes on this molecule. One epitope recognized in the context of H-2b,d was located in the N-terminal part of the molecule, whereas an epitope recognized in the context of H-2a,k covered amino acids 51 to 60. Shorter versions of the N-terminal epitope allowed the precise definition of a 13-amino acid core sequence recognized in the context of H-2b. The peptide covering the N-terminal epitope was immunogenic, and a T cell response with the same fine specificity as that induced during TB infection was generated by immunization with the peptide in IFA. In the C57BL/6j strain, this single epitope was recognized by an exceedingly high frequency of splenic T cells (approximately 1:1000), representing 25 to 35% of the total culture filtrate-reactive T cells recruited to the site of infection during the first phase of the recall response. These findings emphasize the relevance of this Ag in the immune response to TB and suggest that immunologic recognition in the first phase of infection is a highly restricted event dominated by a limited number of T cell clones.
Amino Acid Sequence↗
Clinical evaluation of MPT-64 and MPT-59, two proteins secreted from Mycobacterium tuberculosis, for skin test reagents.
SETTING: Department of Pulmonary Medicine P, Bispebjerg Hospital, Copenhagen, Denmark. OBJECTIVE: To study the ability of two proteins secreted from Mycobacterium tuberculosis, MPT-64 and MPT-59 to induce delayed type hypersensitivity (DTH) reactions following intradermal administration. DESIGN: In a small scale clinical investigation, skin reactions to these antigens were compared to reactions to tuberculin PPD RT23 in 1) patients with active tuberculosis, 2) BCG vaccinated healthy subjects with close contact with tuberculous patients, and 3) BCG vaccinated healthy subjects without contact with tuberculous patients. Tests for in vitro reactivity to these antigens were carried out in similar groups. RESULTS: All subjects gave positive reaction to tuberculin PPD RT23, whereas approximately half of the subjects in each of the three groups reacted to MPT-59. Two subjects (one patient with tuberculosis and one healthy bacille Calmette-Guérin vaccinated subject without patient contact) reacted to MPT-64. The studies of cell proliferation and induction of interferon-gamma (IFN-gamma) following stimulation with tuberculin PPD and MPT-64 supported this profile of reactivity. CONCLUSION: None of the experimental skin test antigens had properties superior to tuberculin PPD RT23 in humans. The failure of MPT-64 to induce delayed type hypersensitivity reactions in the majority of tuberculosis patients is discussed, in view of the potent reactivity to MPT-64 in tuberculous guinea pigs.
Adult↗
Recall of long-lived immunity to Mycobacterium tuberculosis infection in mice.
Our study investigates the recall of immunity in the mouse model of memory immunity to tuberculosis infection. The results provide evidence that recall of immunity is expressed as an accelerated accumulation of potent effector cells in the infected target organs. These effector cells were recruited from the resting pool of memory cells and were immediately triggered to exert their effector functions, leading to a massive release of Th1 cytokines detectable both in splenic extracts and in the serum within the first 24 h of infection. During a primary infection, in contrast, a 14-day delay was observed before significant cytokine levels were reached. After the initial effector phase, the cells blasted and entered into clonal expansion, resulting in a rapid increase in the total number of CD4 CD45RBlow cells in the spleen. The recall of memory immunity was highly efficient and controlled an infectious challenge within the first week. The molecules recognized by the memory effector subset were the proteins secreted from Mycobacterium tuberculosis during growth. By separating the CD4 population into CD45RBhigh and CD45RBlow subsets, the memory effector cells were demonstrated to reside predominantly in the activated population of CD45RBlow CD44high LFA-1high L-selectinlow cells. The key antigenic targets recognized by these cells were identified as Ag85B and a secreted 6-kDa protein (ESAT-6) that elicited the release of exceedingly high levels of IFN-gamma. ESAT-6 was biochemically purified, characterized, and the gene encoding the protein was cloned.
Amino Acid Sequence↗
Humoral response to Mycobacterium tuberculosis-specific antigens in African tuberculosis patients with high prevalence of human immunodeficiency virus infection.
SETTING: The applicability of serodiagnosis of tuberculosis using Mycobacterium tuberculosis-complex-specific antigens in a Tanzanian population with high prevalence of HIV. OBJECTIVE: This study was performed to evaluate the usefulness, sensitivity and specificity of serology using M. tuberculosis-specific antigens in the diagnosis of tuberculosis in patients with and without HIV co-infection. DESIGN: Patients with proven pulmonary and extrapulmonary tuberculosis at a major referral centre in Tanzania were enrolled in the study. The control group consisted of patients without a history of previous tuberculosis admitted to the trauma ward and of healthy volunteers. Sera were analysed by an enzyme linked immunoassay (ELISA) using two M. tuberculosis specific proteins as antigen: the 38 kDa protein [3T] and a 17 kDa protein. In addition was recorded presence or absence of BCG scar and tuberculin sensitivity and the sera were tested for HIV and analysed for beta-2-microglobulin content. RESULT: Sensitivity and specificity were markedly reduced in tuberculosis patients with HIV co-infection compared to patients without this disease (73% and 70% versus 52% and 50% respectively). CONCLUSION: Serology for diagnosis of tuberculosis is not feasible in an HIV endemic region.
Antibodies, Bacterial↗
Molecular composition of the outermost capsular material of the tubercle bacillus.
To gain insight into the pathogenesis of tuberculosis, a molecular definition of the tubercle bacillus cell envelope, which is involved in the early stages of the infection, is required. The cell-surface-exposed material of the pathogen was isolated by mechanical means and chemically analysed. It was shown by scanning electron microscopy that the method used for extracting the surface-covering material preserves the integrity of the bacilli. Surprisingly, in view of the current opinion, only small amounts of lipids (1-6%) were present. Polysaccharides and proteins were the main components of the material. The polysaccharides were neutral and lipid-free D-glucan, D-arabino-D-mannan and D-mannan, which were eluted from gel-filtration columns in positions corresponding to molecular masses of 120, 13 and 4 kDa, respectively. Based on NMR spectroscopy and conventional chemical analyses, the major structural motifs of the purified polysaccharides were established as being identical to those of the polysaccharides we previously isolated from the culture filtrate of the tubercle bacillus. Immunocytochemical studies showed that these compounds were not only surface-located but were also present in the inner capsular compartment. The major protein constituents exhibited the same mobilities on SDS-PAGE as those of the culture filtrate on the tubercle bacillus and readily reacted with the monoclonal antibodies directed against these molecules. These proteins included the 19 and 38 kDa lipoproteins, the 30/31 kDa fibronectin-binding proteins and the 40 kDa L-alanine dehydrogenase. These findings suggest that the culture filtrate material represents part of the capsule which, in an in vivo context, could contribute to the electron transparent zone surrounding the tubercle bacillus. The 24 kDa (MPB/T64) protein was found to be a secreted protein, as it was detected almost exclusively in the culture filtrate. Taken together, the data give a new insight into the surface-exposed compounds of the tubercle bacillus and may explain part of the nature and limitation of the host immunity towards the pathogen.
Antigens, Bacterial↗
Mapping of the delayed-type hypersensitivity-inducing epitope of secreted protein MPT64 from Mycobacterium tuberculosis.
The gene encoding the immunogenic protein MPT64 found in culture filtrates of Mycobacterium tuberculosis H37Rv was expressed in Escherichia coli K-12 and purified as a recombinant protein. The purified recombinant MPT64 elicited delayed-type hypersensitivity (DTH) in outbred guinea pigs sensitized with Mycobacterium bovis BCG Tokyo. The skin reactions were comparable to those obtained with native MPT64. No skin reactions were observed when either recombinant MPT64 or native MPT64 was used in guinea pigs sensitized with M. bovis BCG Danish 1331. Amino- and carboxy-terminal deletion mutants of MPT64 were purified as fusion proteins for the mapping of DTH-inducing epitopes on recombinant MPT64 by use of the guinea pig skin test model. The part of the molecule responsible for the biological activity was located at the carboxy-terminal end. Further studies with overlapping synthetic peptides have pinpointed the biological activity at a single DTH-inducing epitope consisting of 15 residues between amino acids Gly-173 and Ala-187. Screening by PCR of 56 clinical isolates of M. tuberculosis from Danish and Tanzanian patients demonstrated the presence of mpt64 in all of the strains. These results point to MPT64 as a possible candidate for a skin test reagent specific for diagnosis of human tuberculosis.
Amino Acid Sequence↗
Purification and characterization of a low-molecular-mass T-cell antigen secreted by Mycobacterium tuberculosis.
A novel immunogenic antigen, the 6-kDa early secretory antigenic target (ESAT-6), from short-term culture filtrates of Mycobacterium tuberculosis was purified by hydrophobic interaction chromatography and anion-exchange chromatography by use of fast protein liquid chromatography. The antigen focused at two different pIs of 4.0 and 4.5 during isoelectric focusing, and each of these components separated into three spots ranging from 4 to 6 kDa during two-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The apparent differences in molecular masses or pIs of these isoforms were not due to posttranslational glycosylation. The molecular weight of the purified native protein was determined by applying gel filtration and nondenaturing polyacrylamide gel electrophoresis and found to be 24 kDa. ESAT-6 is recognized by the murine monoclonal antibody HYB 76-8, which was used to screen a recombinant lambda gt11 M. tuberculosis DNA library. A phage expressing a gene product recognized by HYB 76-8 was isolated, and a 1.7-kbp fragment of the mycobacterial DNA insert was sequenced. The structural gene of ESAT-6 was identified as the sequence encoding a polypeptide of 95 amino acids. The N terminus of the deduced sequence could be aligned with the 10 amino-terminal amino acids derived from sequence analyses of the native protein. N-terminal sequence analysis showed that the purified antigen was essentially free from contaminants, and the amino acid analysis of the antigen was in good agreement with the DNA sequence-deduced amino acid composition. Thus, the heterogeneities observed in the pI and molecular weight of the purified antigen do not derive from contaminating proteins but are most likely due to heterogeneity of the antigen itself. Native and recombinant ESAT-6 are immunologically active in that both elicited a high release of gamma interferon from T cells isolated from memory-immune mice challenged with M. tuberculosis. Analyses of subcellular fractions of M. tuberculosis showed the presence of ESAT-6 in cytosol- and cell wall-containing fractions. Interspecies analyses showed the presence of ESAT-6 in filtrates from M. tuberculosis complex species. Among filtrates from mycobacteria not belonging to the M. tuberculosis complex, reactivity was observed in Mycobacterium kansasii, Mycobacterium szulgai, and Mycobacterium marinum.
Amino Acid Sequence↗
Molecular epidemiology of tuberculosis in Denmark in 1992.
The incidence of tuberculosis (TB) is increasing all over the world, including in countries with a high standard of living and good social security. Denmark represents such a region. Furthermore, it is a small country (5 million inhabitants) with a long tradition in TB control, including a centralization of the bacteriological diagnostic facility. The present study was intended to analyze the transmission of Mycobacterium tuberculosis in a country in which TB has low endemicity by a combination of conventional epidemiological approaches and DNA fingerprinting techniques, whereby individual bacterial strains can be traced. M. tuberculosis isolates from 92% of all new cases of bacteriologically verified TB in Denmark during 1992 were subjected to IS6110 DNA fingerprinting to visualize the DNA restriction fragment length polymorphism (RFLP) patterns of the isolated strains. The data obtained from the RFLP analyses were interpreted by using demographic data, such as age, sex, ethnicity, and residence, for the patients. The risk factors among the patients for being part of an active chain of transmission, as opposed to demonstrating reactivation of a previously acquired latent infection, were estimated by statistical analyses. The magnitude of TB transmission in 1992 in Denmark was determined, and transmitted infections were shown to comprise at least one quarter of the total number of cases. Almost half of the TB cases involved patients of foreign origin. However, most of these isolates showed unique DNA fingerprint patterns and were rarely part of an active chain of transmission. The major chains of recent transmission were localized to distinct geographical regions in the country. TB is frequent among immigrants, especially from Asia and Africa, but it is apparently readily suspected, diagnosed, and treated by the health care system. Danish patients with pulmonary symptoms are not primarily suspected to have TB and, therefore, play an important role in recent TB transmission in Denmark.
Adolescent↗
Proctocolectomy and quadruple-limb W pouch reconstruction for the management of pediatric ulcerative colitis and familial polyposis.
Proctocolectomy with ileal pouch-anal anastomosis (IPAA) has become the procedure of choice for many children with ulcerative colitis and familial polyposis. The modified quadruple-limb (W) IPAA was designed to increase reservoir compliance and capacity, and to improve functional results by decreasing stool frequency. However, only limited information has been reported concerning the technical considerations and functional outcomes from W IPAA modification and utilization in the pediatric population. Additionally, pediatric IPAA physiological adaptation, expressed as IPAA volume/pressure relationships, for any type of IPAA design has not been described. In this report, the authors analyze their functional and physiological results with W IPAA in 19 children undergoing colectomy for ulcerative colitis and familial polyposis. Since 1986, 19 children (5 girls, 14 boys; mean age, 15.3 years [range, 11 to 18 years]) have undergone proctocolectomy with W IPAA for ulcerative colitis (n = 9) and familial polyposis (n = 10). IPAA pressure and volume profiles were measured in 10 patients at 2 and 12 months postileostomy takedown, and in five patients at 3 years. W IPAA compliance was calculated as the change in volume over change in pressure (delta V/delta P). There were no deaths, anastomotic leaks, or pelvic sepsis. The 24-hour stool frequency (mean +/- SEM) decreased significantly (P < or = .05) from 4.6 +/- 0.6 at 2 months to 3.3 +/- 0.1 at 12 months. No nighttime evacuation occurred after 12 months. W IPAA evacuation volume significantly increased (P < or = .05) from 238 +/- 22.9 mL at 2 months to 346 +/- 26.5 mL at 12 months and remained stable thereafter.(ABSTRACT TRUNCATED AT 250 WORDS)
Adaptation, Physiological↗
Characterization of purified protein derivative of tuberculin by use of monoclonal antibodies: isolation of a delayed-type hypersensitivity reactive component from M. tuberculosis culture filtrate.
Nine monoclonal antibodies were raised against purified protein derivative (PPD) of tuberculin in mice previously treated with Bacilli Calmette Guérin (BCG). The antibodies also reacted with a culture filtrate from Mycobacterium tuberculosis strain H37Rv. In immunoblotting after SDS-PAGE the reaction with PPD was seen as a diffuse smear, whereas ammonium sulphate-precipitated proteins from H37Rv gave well-defined bands ranging from 10 to 65 kDa. Enzyme immunoassay showed that both PPD and H37Rv antigens were able to inhibit binding of the antibodies to PPD coated microtitre wells, suggesting that the antibodies reacted with continuous epitopes. A 12 kDa protein purified by immunoaffinity chromatography from H37Rv antigens was tested intradermally in M. tuberculosis MNC3 sensitized guinea pigs and gave a delayed type hypersensitivity reaction.
Animals↗
Cloning and B-cell-epitope mapping of MPT64 from Mycobacterium tuberculosis H37Rv.
The gene of the immunogenic protein MPT64 found in culture filtrates of Mycobacterium tuberculosis H37Rv was cloned and sequenced. A comparison showed mpt64 and the gene encoding MPB64 from Mycobacterium bovis BCG Tokyo to be identical except for one silent mutation. The regions encoding the promoter and the signal peptide were also well conserved for the two sequences. Southern blot experiments on genomic mycobacterial DNA showed the presence of mpt64 in the M. tuberculosis substrains H37Rv, H37Ra, and Erdman and in the M. bovis BCG substrains Tokyo, Moreau, and Russian, whereas the M. bovis BCG substrains Glaxo, Pasteur, Canadian, Tice, and Danish 1331 and Mycobacterium leprae lack the gene. Southern blot analyses revealed differences in the restriction enzyme patterns within the M. tuberculosis substrains as well as within the M. bovis BCG substrains, indicating either different chromosomal localization of mpt64 or that mutations have occurred at different locations on the chromosomes. N-terminal and C-terminal deletion mutants were constructed for the mapping of B-cell epitopes on MPT64 with five monoclonal antibodies, C24b1, C24b2, C24b3, L24b4, and L24b5. Western blot (immunoblot) analysis revealed that the murine antibodies bind to one linear and three conformational epitopes.
Amino Acid Sequence↗
Restriction fragment length polymorphism Mycobacterium tuberculosis strains isolated from Greenland during 1992: evidence of tuberculosis transmission between Greenland and Denmark.
In order to describe the transmission of tuberculosis (TB) at the clonal level in a defined geographic region during a certain period of time, all isolates of Mycobacterium tuberculosis collected during 1992 from Greenland were subjected to analyses of DNA restriction fragment length polymorphism (RFLP). The RFLP patterns obtained by probing the genomic DNA with the repetitive insertion segment IS6110 revealed a high degree of similarity among the isolates, indicating a relatively high transmission rate and a close relationship between the individual M. tuberculosis clones. This was further confirmed by reprobing the Southern blots with two more-stable genetic markers, IS1081 and the DR sequence. The RFLP patterns were compared with those of 245 M. tuberculosis strains collected from Denmark during the same period (representing 91% of all new, bacteriologically verified cases of TB in Denmark in 1992). One of the three prevalent IS6110-defined clusters was traced to a group of immigrants from Greenland living in a small, defined geographical region in Denmark and to a group of Danish citizens either with known contact with these immigrants or, in other cases, with a record of previous travel or working activities in Greenland. The study showed that the present technique is extremely helpful in monitoring the spread of TB and thereby also contributing to improved disease control.
Cross-Sectional Studies↗