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L Hübner

Publications and source records attributed to L Hübner.

18 recordsLinked to original sources
PubMed1995

Cytokines in mycobacterial infections: in vitro and ex vivo studies.

Different species of mycobacteria differ in their capacity to induce the production of tumor necrosis factor-alpha (TNF-alpha) by human monocytes in vitro. Whereas M. tuberculosis is a potent inducer of TNF-alpha, M. leprae is much less potent. TNF-alpha production is found to be associated with the availability of H2O2 generated by activated monocytes, as superoxide enhancing H2O2 concentration increases and catalase degrading H2O2 decreases TNF-alpha production. Furthermore, M. kansasii with high intrinsic catalase induce less TNF-alpha than mycobacteria with low intrinsic catalase. In vitro infection of monocytes with M. tuberculosis leads to an impairment of the antigen-presenting capacity, as determined by a reduction of antigen-induced T cell proliferation and interferon gamma (IFN-gamma) production. Of crucial importance is this impairment is the M. tuberculosis-induced down-modulation of MHC class II antigens. The role of TNF-alpha in vivo is reflected in patients with various forms of leprosy. In skin lesions of lepromatous leprosy patients TNF-alpha, interleukin 1 beta (IL-1 beta), and INF-gamma production are found to be rare, whereas these cytokines are well expressed in skin lesions of patients with tuberculoid leprosy. After multidrug chemotherapy an increase of local cytokine production is found. Taken together, these findings suggest that components of mycobacteria may interfere with local cell-mediated immune reactions in vivo. The molecular mechanisms involved in these local responses need to be defined.

Antigen-Presenting Cells↗
PubMed1992

Species-specific assessment of Mycobacterium leprae in skin biopsies by in situ hybridization and polymerase chain reaction.

Conventional histopathologic diagnosis of mycobacterial infections are limited to the determination of "acid-fast bacilli". A species-specific diagnosis is thus far impossible. In addition, routine microbiologic assessments of mycobacteria suffer from the major drawback that a species-specific diagnosis is extremely time-consuming and in several cases even impossible. As Mycobacterium leprae cannot be cultured in vitro, we tried to specifically target this obligate intracellular parasite by in situ hybridization and polymerase chain reaction (PCR) techniques. For this purpose we used a 22 mer oligonucleotide probe recognizing a species-specific sequence of the 16S rRNA of Mycobacterium leprae. Using an immunoenzymatic detection method for in situ hybridization we were able to specifically assess Mycobacterium leprae (a) in long-term cultured macrophages in vitro infected with different mycobacteria species and (b) in frozen sections of skin biopsies obtained from patients suffering from lepromatous leprosy. These results could be confirmed and extended by PCR experiments in which we used conserved oligonucleotide primers for 16S rRNA to amplify bacterial DNA isolated from different eubacterial species and from fresh-frozen as well as from formalin-fixed, paraffin-embedded and routinely processed mycobacteria-infected tissues. Upon Southern blot analysis, the Mycobacterium leprae-specific oligonucleotide probe exclusively hybridized with PCR products obtained from Mycobacterium leprae-containing samples (including paraffin sections), but not with PCR products obtained from samples containing other mycobacterial species. As species-specific oligonucleotide probes targeted at rRNA are described for a variety of mycobacterial species, these methods may be generally applied for a rapid species-specific assessment of mycobacteria in histologic material.

Base Sequence↗
PubMed1991

Enhancement of monocyte antimycobacterial activity by diethyldithiocarbamate (DTC).

Diethyldithiocarbamate (DTC) has been recently reported to significantly reduce the incidence of opportunistic infections in HIV-infected patients. The present study addresses the question whether DTC is capable of stimulating antimycobacterial activity of mononuclear phagocytes. We found that peripheral blood mononuclear cells (PBMC) of healthy subjects preincubated in vitro with 100-1000 ng/ml of DTC and thereafter infected with Mycobacterium tuberculosis H37Rv or Mycobacterium avium-intracellulare complex exhibited an enhanced antimycobacterial activity compared with control-incubated cells as assessed by the determination of mycobacterial colony-forming units. In subsequent experiments monocytes from healthy volunteers injected with 5 mg/kg body weight of DTC were tested ex vivo for antimycobacterial activity at various periods of time after injection. Injection of DTC resulted in a significant enhancement of antimycobacterial activity which was most evident 24 h after DTC injection. We conclude that DTC stimulates the antimicrobial function of mononuclear phagocytes both in vitro and in vivo. These results may explain the favourable clinical course observed in HIV-infected patients treated with DTC and may serve as a basis for treatment with DTC in patients with drug-resistant atypical mycobacteriosis.

Blood Bactericidal Activity↗
PubMed1988

[Metastasis of cervical cancer to the end phalanx of the small finger].

Case report on a diabetic patient aged 68 years, who was operated on a cervical carcinoma by the method of Wertheim-Meigs. 3 weeks later a panaritium of the right little finger developed. X-ray examination resulted an osteoclastic process. The histology of the amputated end limb of this finger demonstrated a metastasis of a squamous cell carcinoma. The patient died 49 days after operation. Autopsy found a massive development of tumor with multiple far metastases.

Aged↗
PubMed1980

Chemical characterization of macrophage cytotoxicity factor, macrophage migration inhibitory factor, T-helper cell-replacing factor and colony-stimulating factor from culture supernatants of concanavalin A-stimulated murine spleen cells.

Supernatants from Concanavalin A-stimulated murine spleen cells were subjected to hydrophobic interaction chromatography on phenyl-Sepharose. Macrophage cytotoxicity factor (MCF), macrophage migration inhibitory factor (MIF), T-helper cell-replacing factor (TRF) and colony-stimulating factor (CSF) were bound at high ionic strength and were released stepwise at low ionic strength. CSF thus could be separated from MCF, MIF and TRF and the bulk of other proteins. Chromatograhy of pools containing MCF, MIF and TRF on Sephadex did not lead to a separation of the three activities which were all found in a molecular weight range of 25.000-55.000. Isoelectric focusing of these pools in pH range from 4 to 9 gave two peaks for MCF in a single sharp peak at pH 5.3. The results demonstrate that the four biological activities can be distinguished on a chemical basis and are accessible for purification and chemical characterization.

Animals↗