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G Källenius

Publications and source records attributed to G Källenius.

At least 37 records · Page 2Linked to original sources
PubMed1999

Synthesis and immunologic characterisation of Mycobacterium tuberculosis lipoarabinomannan specific oligosaccharide-protein conjugates.

Lipoarabinomannan (LAM) is a major structural surface component of all mycobacteria, and has been reported to have a wide range of biological effects. Immunogenic LAM specific oligosaccharide protein conjugates were synthesized and immunologically characterized. Oligosaccharides were derived from LAM purified from Mycobacterium tuberculosis H37 Rv and covalently conjugated to tetanus toxoid and cross reactive mutant (CRM197) diphtheria toxoid. Both types of LAM oligosaccharide protein conjugates proved to be highly immunogenic, inducing a boosterable T helper cell dependent IgG response. These conjugates are currently evaluated as components in a subcellular experimental TB vaccine.

Animals↗
PubMed1999

A new method of non-cross-linking conjugation of polysaccharides to proteins via thioether bonds for the preparation of saccharide-protein conjugate vaccines.

Bacterial polysaccharides, including capsular polysaccharides, are poor immunogens particularly in young infants. However, conjugation of bacterial polysaccharides to immunogenic carrier proteins generally results in conjugates that induce strong antipolysaccharide T-helper-cell dependent immune responses, also in young infants. The magnitude of the response and the extent of the T-helper-cell dependency is related to the chemical characteristics of the particular conjugate such as presence or absence of polysaccharide-protein cross-linking, presence or absence of spacer arms, character of spacer arms, type of carrier protein, size of conjugated polysaccharide hapten and molar degree of substitution. In the present study a new, general and simple method for the preparation of poly- and oligosaccharide-protein conjugates is presented. This new method is based on spacer-introducing chemistry that allowed for conjugation of a model polysaccharide, dextran, ranging in size from 0.5 to 150 kDa, to tetanus toxoid (TTd). The developed conjugation method involves derivatization of polysaccharide with 2-iminothiolane (2-IT) and activation of carrier protein, such as TTd, with N-hydroxysuccinimide ester of bromoacetic acid. Reaction rates and accordingly the substitution of the conjugates, could be controlled by varying time, pH and concentration of the reactants. Unlike direct reductive amination, the 2-IT based conjugation technology is fast and made it possible to couple fairly large polysaccharides to TTd.

Dextrans↗
PubMed1999

A new rapid and simple method for large-scale purification of mycobacterial lipoarabinomannan.

Lipoarabinomannan (LAM) is a major and structurally important outer cell wall component of all mycobacteria. LAM is also generally regarded as an important immunomodulating substance affecting several immunologic networks and hence important in the pathogenesis of mycobacterial infections. We here describe a new method for large-scale purification of mycobacterial LAM. A crude cell wall preparation was prepared from batch-grown Mycobacterium tuberculosis H37Rv. From this cell wall preparation LAM was purified by sequential extractions and chromatographic steps. From 20 g dry weight cell wall preparation 313 mg of highly purified (> 98%) LAM was obtained in only 3 days. The LAM content of the final purification step was quantified by ELISA using reference LAM as standard. The identity and purity of the LAM preparation was further confirmed by comparison with reference LAM preparation from M. tuberculosis strain Erdman in polyacrylamide gel electrophoresis and Western blots, using reference anti-LAM monoclonals CS-35 and CS-40.

Antigens, Bacterial↗
PubMed1999

Evolution and clonal traits of Mycobacterium tuberculosis complex in Guinea-Bissau.

Two hundred twenty-nine consecutive isolates of Mycobacterium tuberculosis complex from patients with pulmonary tuberculosis in Guinea-Bissau, which is located in West Africa, were analyzed for clonal origin by biochemical typing and DNA fingerprinting. By using four biochemical tests (resistance to thiophene-2-carboxylic acid hydrazide, niacin production, nitrate reductase test, and pyrazinamidase test), the isolates could be assigned to five different biovars. The characteristics of four strains conformed fully with the biochemical criteria for M. bovis, while those of 85 isolates agreed with the biochemical criteria for M. tuberculosis. The remaining 140 isolates could be allocated into one of three biovars (biovars 2 to 4) representing a spectrum between the classical bovine (biovar 1) and human (biovar 5) tubercle bacilli. By using two genotyping methods, restriction fragment length polymorphism analysis with IS6110 (IS6110 RFLP analysis) and spoligotyping, the isolates could be separated into three groups (groups A to C) of the M. tuberculosis complex. Group A (n = 95), which contained the majority of classical human M. tuberculosis isolates, had large numbers of copies of IS6110 elements (mean number of copies, 9) and a distinctive spoligotyping pattern that lacked spacers 33 to 36. Isolates of the major group, group B (n = 119), had fewer IS6110 copies (mean copy number, 5) and a spoligotyping pattern that lacked spacers 7 to 9 and 39 and mainly comprised isolates of biovars 1 to 4. Group C isolates (n = 15) had one to three IS6110 copies, had a spoligotyping pattern that lacked spacers 29 to 34, and represented biovar 3 to 5 isolates. Four isolates whose biochemical characteristics conformed with those of M. bovis clustered with the group B isolates and had spoligotype patterns that differed from those previously reported for M. bovis, in that they possessed spacers 40 to 43. Interestingly, isolates of group B and, to a certain extent, also isolates of group C showed a high degree of variability in biochemical traits, despite genotypic identity in terms of IS6110 RFLP and spoligotype patterns. We hypothesize that isolates of groups B and C have their evolutionary origin in West Africa, while group A isolates are of European descent.

Adult↗
PubMed1998

Gammadelta+ and CD4+ alphabeta+ human T cell subset responses upon stimulation with various Mycobacterium tuberculosis soluble extracts.

By using a flow cytometric technique which allows direct identification of proliferating cells within mixed cell populations, we have previously described that soluble extracts obtained from Mycobacterium tuberculosis or M. avium represent strong stimuli for human gammadelta+ T cells. In the present study, we demonstrate that the protocol used for the preparation of M. tuberculosis soluble extracts may have an impact on their gammadelta+ T cell stimulatory capacity. In agreement with our previous data, soluble extracts prepared from bacteria killed at 85 degrees C and directly disrupted by prolonged sonication (TBe), elicited a strong proliferation of gammadelta+ T cells after 6-7 days of stimulation. In contrast, when soluble extracts were obtained from bacteria autoclaved (121 degrees C, 25 min) and then washed by centrifugation, a predominant proportion of CD4+ alphabeta+ T cells was achieved in the responding population. The stimulatory activity for gammadelta+ T cells was recovered in the supernatant of the autoclaved bacteria, indicating that autoclaving of M. tuberculosis bacilli releases an antigen(s) into the supernatant which stimulates human gammadelta+ T cells. While protease digestion of TBe only partially reduced its stimulatory capacity on gammadelta+ T cells, the stimulatory component(s) released into the supernatant after autoclavation of bacilli was found to be sensitive to protease digestion. Interestingly, in contrast to the preponderant proportion of gammadelta+ T cells induced in the responding population by unfractionated TBe, when the extract was fractionated by fast performance liquid chromatography (FPLC), most of the fractions exhibited a strong stimulatory capacity on CD4+ alphabeta+ T cells only. The gammadelta+ T cell stimulatory activity was confined to the low molecular weight range FPLC fractions. Such results may suggest a possible regulatory role of gammadelta+ T cells on CD4+ alphabeta+ T cells.

Antigen Presentation↗
PubMed1998

Drug resistant tuberculosis in Estonia.

SETTING: The incidence of drug resistant tuberculosis in Estonia has increased rapidly during the last five to six years. OBJECTIVE: To investigate the drug resistance patterns of Mycobacterium tuberculosis isolated from tuberculosis patients in Estonia. RESULTS: In 1994, 623 cases of tuberculosis were diagnosed in Estonia, 518 new cases with no previous history of tuberculosis, and 105 with a history of previous treatment for tuberculosis. All pulmonary M. tuberculosis isolates from 1994 were analysed for drug susceptibility. Of the 302 new cases (58.3%) that were culture verified, 28% had isolates resistant to one or more of the four drugs tested (isoniazid, rifampicin, streptomycin, ethambutol), and 9% had multi-drug resistant (resistant to at least isoniazid and rifampicin) strains. CONCLUSION: The incidence of drug resistance in M. tuberculosis is high in Estonia.

Adult↗
PubMed1997

Mycobacterium fortuitum complex in Sweden during an 11-year period.

Records of patients have been retrospectively examined studied during an 11-y period, from whom Mycobacterium fortuitum or M. chelonae was isolated in Sweden. Respiratory isolates were obtained from 71 patients. Clinical information was accessible in 52, chest X-ray was pathological in 51, and 42 had underlying diseases. Four skin and 4 urine isolates were observed. Two cases of osteitis and 2 bone marrow isolates of M. chelonae were found. One girl had a submandibular lymph node abscess with M. fortuitum. Of 2 HIV patients, 1 had positive blood cultures with M. fortuitum and the other positive sputum culture with M. chelonae. The broad spectrum of infections with M. fortuitum complex necessitates an integrated judgement of clinical and bacteriological data to determine the relevance of such isolates.

Adult↗
PubMed1996

Pulmonary tuberculosis in Guinea-Bissau: clinical and bacteriological findings, human immunodeficiency virus status and short term survival of hospitalized patients.

OBJECTIVE: To study tuberculosis patients in Guinea-Bissau with regard to clinical findings, bacteriologically verified diagnosis, human immunodeficiency virus (HIV) status and short term survival. DESIGN: 763 consecutive patients referred to the tuberculosis clinic with pulmonary symptoms underwent clinical examination and Ziehl-Neelsen sputum microscopy. Sputum for culture of mycobacteria on Löwenstein-Jensen medium was collected from all hospitalized patients, who were also screened by enzyme linked immunosorbent assay for the presence of HIV-1 and HIV-2 antibodies. HIV-positivity was confirmed by Western blot. RESULTS: 350 patients were diagnosed with tuberculosis and hospitalized. Adequate sputum samples were obtained from 301 patients, of whom 184 (61%) were positive on direct microscopy and the remaining 116 patients were diagnosed from clinical findings. Mycobacterium tuberculosis was cultured from 184 patients and M. avium in 16 patients, whereas in 101 patients the culture was negative. HIV-1 antibodies were found in 3.0%, HIV-2 antibodies in 16.4%, and dual infections in 2.0%. These figures, however, did not differ significantly from those of randomly selected age and sex matched controls. The prevalence of HIV-antibodies was statistically as common in patients with culture verified tuberculosis as in patients with clinically defined tuberculosis. Clinical acquired immunodeficiency syndrome was commonly diagnosed (80/301 patients) but significantly more often in HIV-positive, culture-positive tuberculosis patients, as were weight loss and lymphadenopathy. There was no statistical difference in short-time survival rate between the various patient groups. CONCLUSION: The diagnostic criteria applied, which are generally used in developing countries, identified most patients with pulmonary tuberculosis; however, a substantial number of patients are treated for tuberculosis without definite diagnostic criteria. The prevalence of HIV-infection was high but statistically no significant difference was demonstrated between the patient groups, controls and patients hospitalized for diseases other than tuberculosis.

AIDS-Related Opportunistic Infections↗
PubMed1996

Direct detection of Mycobacterium tuberculosis in sputum samples from Guinea Bissau by an rRNA target-amplified test system.

SETTING: There is a need for more sensitive and rapid methods for laboratory confirmation in the diagnosis of tuberculosis. OBJECTIVE: To investigate the applicability of a target rRNA amplified test system (AMTDT, Gen-Probe, CA) for rapid detection of Mycobacterium tuberculosis. DESIGN: The rRNA amplified test system was compared to standard methods for acid fast microscopy and mycobacterial culture for the demonstration of M. tuberculosis in sputum samples from 247 patients in Guinea Bissau with suspected tuberculosis. RESULTS: The highest incidence of positive samples was obtained with the AMTDT test. Out of 274 sputum samples 96 (35%) were positive by the AMTDT test, 82 (30%) were positive by culture and 38 (14%) by direct microscopy. Using culture as reference method the sensitivity of the test was 85% (after discrepancy analysis 87%), and the specificity was 86% (after discrepancy analysis 93%). CONCLUSION: The sensitivity and specificity of the AMTDT test used in this setting indicates that it may be a valuable complement for improving the laboratory diagnosis of tuberculosis.

Bacteriological Techniques↗
PubMed1996

Proliferation of distinct human T cell subsets in response to live, killed or soluble extracts of Mycobacterium tuberculosis and Myco. avium.

The proliferative responses of distinct cell subsets from healthy, bacille Calmette-Guérin (BCG)-vaccinated blood donors were assessed after in vitro stimulation with live or UV-killed Mycobacterium tuberculosis and Myco. avium or with soluble extracts obtained from either mycobacterial species. Proliferation of cell subsets was evaluated by flow cytometric determination of 5-bromo-2'-deoxy-uridine incorporation into DNA and simultaneous identification of surface phenotypic markers. In the presence of monocytes, the response to whole (live or killed) bacteria was characterized by a predominant proliferation of CD4+ alphabeta+ T cells and, to a lesser extent, of CD8+ alphabeta+ T cells. Proliferation of CD8+ alphabeta+ T cells was primarily elicited by live rather than killed bacilli (P < 0.05). Conversely, when soluble bacterial extracts were used as stimulators, a preferential proliferation of gammadelta+ T cells, expressing predominantly Vgamma9+ and Vdelta2+ T cell receptor chains, was recorded. Moreover, when monocyte-depleted cell populations were directly cultured with live bacteria, a marked proportion of CD3- CD16+ (natural killer (NK)) cells was detected among the responding cells. Although both alphabeta, gammadelta and NK cells have been previously shown to react with mycobacteria in vitro, their relative contributions to the response have been difficult to assess. Using a flow cytometric technique which allows direct identification of proliferating cells within complex cell populations, our study demonstrates significant differences in the ability of various mycobacterial antigen preparations to elicit proliferation of distinct cell subsets.

Antigens, Bacterial↗
PubMed1996

Mycobacterium avium complex sputum isolates from patients with respiratory symptoms in Guinea-Bissau.

In total, 814 patients with clinically suspected tuberculosis were examined at the Raoul Follerau Hospital in Bissau, Guinea-Bissau. Sputum samples were collected, and cultures were grown on Löwenstein-Jensen medium. Isolates were further characterized by standard biochemical methods and nucleic acid probes for Mycobacterium tuberculosis and Mycobacterium avium complex (MAC). Serum samples were collected and analyzed for antibodies against human immunodeficiency virus (HIV) types 1 and 2. Of 17 patients who had MAC organisms in sputum, 2 were HIV-2-positive and none was HIV-1-positive. Of the total 814 patients, 189 had culture-verified tuberculosis; 36 (19%) of them were HIV-2-positive. Thus, of 206 patients with sputum culture positive for M. tuberculosis or MAC, 17 (8%) had MAC organisms in sputum. MAC infection may be the cause of some treatment failures in areas where MAC pulmonary infection is common.

Adult↗
PubMed1996

Antimycobacterial synergism of clarithromycin and rifabutin.

Clarithromycin and rifabutin are among the most promising drugs for the therapy of infections caused by Mycobacterium avium or other atypical mycobacteria. Since synergism of combined drugs is important in order to achieve strong antimycobacterial activity, the combined inhibitory effects of antibacterial agents should also be investigated when agents are evaluated for possible use in antimycobacterial drug therapy. In the present study we examined the antimycobacterial activity of clarithromycin, rifabutin, and their combination against 51 clinical isolates of the M. avium complex from patients with acquired immune deficiency syndrome (AIDS) with disseminated mycobacteriosis. A concentration-dependent inhibition was seen for each drug. The antibacterial effect was significantly more pronounced for the combined drugs than for the agents tested separately. Synergism, against up to 88% of the strains tested, was seen for the tested drugs combined at different concentrations. All 51 M. avium strains were susceptible to the combination of 4 mg/l clarithromycin and 2 mg/l rifabutin.

AIDS-Related Opportunistic Infections↗
PubMed1995

Incidence, capsular types, and antibiotic susceptibility of invasive Streptococcus pneumoniae in Sweden.

The number of reported cases of invasive pneumococcal infections in Sweden increased more than threefold from 1988 through 1992. We studied the capsular types and the antibiotic susceptibility of 619 pneumococcal strains isolated from blood or CSF at 18 Swedish microbiological laboratories in 1987 and in 1992. These strains belonged to 35 of the 84 recognized capsular types. We noted a remarkable increase in the prevalence of invasive infections with type 14 from 1987 (8.2%) to 1992 (18%) (P = .001), which correspond to a sevenfold increase in absolute numbers. The most prominent increase in infections was seen among elderly people; in 1992, type 14 accounted for 22.5% of the isolates from infected persons who were >64 years of age. The majority of the strains were susceptible to all antibiotics tested. However, there was a significant increase in trimethoprim-sulfamethoxazole resistance from 1.4% in 1987 to 7.1% in 1992. Nine multiresistant isolates (1.5%) were found.

Adolescent↗
PubMed1995

Molecular epidemiological studies of Mycobacterium bovis infections in humans and animals in Sweden.

Forty-nine isolates of Mycobacterium bovis from humans and animals in Sweden were analyzed by restriction fragment length polymorphism (RFLP) patterns probed by the insertion element IS6110. Most isolates had patterns indicating the presence of only one or two genomic copies of the IS6110 insertion element. This simple type of pattern was found in all human isolates. In contrast, isolates from M. bovis infections in five herds of farmed deer in Sweden showed a specific RFLP pattern with seven bands, indicating seven copies of the IS6110 sequence. In 1958, Sweden was declared free from M. bovis in cattle. However, in 1987, M. bovis was reintroduced with imported farmed deer, and since 1991, 11 outbreaks in deer herds, but not in other livestock or wildlife, have been diagnosed. Continued RFLP studies of the new Swedish M. bovis isolates can reveal possible transmission of this deer strain to other animals or humans.

Animals↗
PubMed1994

Infection with Mycobacterium malmoense in Sweden: report of 221 cases.

Mycobacterium malmoense was first described in 1977 and today is second only to the Mycobacterium avium complex as a cause of atypical mycobacterial infection in Sweden. We retrospectively studied the records of 221 patients from whom M. malmoense was isolated during 1968-1989. M. malmoense was recovered from the respiratory tract of 171 patients (170 adults and one child) and from cervical lymph nodes of 36 patients (35 children and one adult). In addition, the organism was isolated from the urine of six patients, one of whom had disseminated disease and two of whom had abscesses caused by M. malmoense. A majority of the patients with pulmonary infection as well as the patient with disseminated disease had other underlying diseases.

Adult↗
PubMed1994

Mycobacterium avium complex develop resistance to synergistically active drug combinations during infection.

Isolates of Mycobacterium avium complex from five patients on longterm (3-5 yrs) anti-mycobacterial drug treatment were collected during the early and late phase of disease, and studied in vitro for their susceptibility to anti-mycobacterial drugs and drug-combinations. All isolates were resistant or moderately resistant to ethambutol, rifampicin and streptomycin when given singly; however, all strains isolated early in the disease were susceptible to the combination of ethambutol with either rifampicin or streptomycin. All late isolates had developed resistance to one or both of these combinations. Three of the patients died within a year after the last isolation of M. avium complex, and the two remaining patients still have severe chronic disease. It is concluded that the susceptibility of M. avium strains to combinations of drugs should be monitored during the course of treatment, in order to guide the selection of effective drug-combinations throughout the infection.

Aged↗