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Biomedical subjects

M Schlaak

Publications and source records attributed to M Schlaak.

At least 55 records · Page 3Linked to original sources
PubMed1999

Analysis of the Kveim-Siltzbach test reagent for bacterial DNA.

The sarcoid spleen-derived reagent for the Kveim-Siltzbach test (KST) elicits a sarcoid-specific, granulomatous, cutaneous response used to establish the diagnosis of sarcoidosis. In the context of the ongoing discussion of a bacterial cause of sarcoidosis we asked the question whether bacterial DNA could be found in the KST reagent. For this purpose two different KST reagents, an identical preparation from a normal spleen, and a native sarcoid spleen were analyzed by polymerase chain reaction (PCR) employing universal primers detecting conserved DNA sequences coding for bacterial ribosomal 16S RNA. Neither KST reagents, the control preparation, nor the spleen yielded a positive signal, indicating that the preparations are free of bacterial contamination. Because the KST reagent elicits granuloma, these results do not support the hypothesis of a bacterial cause of sarcoid granuloma.

Conserved Sequence↗
PubMed1999

Extensive mediastinal lymphadenopathy in an adult immunocompetent woman caused by Mycobacterium avium complex.

We report a case of extensive mediastinal lymphadenopathy in a 29-year-old immunocompetent woman, which was thought to be caused by Mycobacterium tuberculosis (MTB). Chest radiographs showed deterioration while the patient was receiving antituberculous medication for 8 months. After isolation of Mycobacterium avium complex (MAC) from a lymph node aspiration biopsy and switch to a MAC-specific therapeutic regimen, the lesion almost completely disappeared within 1 year. To our knowledge, this is the first report of an extensive mediastinal lymphadenopathy caused by MAC in an immunocompetent adult.

Adult↗
PubMed1999

Age-related decrease in accessory cell function of human alveolar macrophages.

BACKGROUND: Suboptimal function of an aged immune system may significantly contribute to morbidity and mortality in the elderly. In contrast to lymphocytes, only little is known about changes of cells from the monocyte/macrophage lineage. Especially the changes of their accessory function, which are necessary for optimal T cell stimulation are controversially discussed. METHODS: We measured the accessory function of monocytes (PBM) and alveolar macrophages (AM) and correlated their accessory function with the age of the patients. RESULTS: We found a significant decrease in accessory function of AM with the age (rs = -0.5, P < 0.006) but not of PBM (rs = -0.4, P > 0.1). Additionally, we found a significant decrease in the percentage of AM (rs = 0.3, P < 0.005) and an increase in the percentage of lymphocytes (rs = 0.3, P < 0.02) in the bronchoalveolar lavage. No correlations could be found with other lavage parameters or with unstimulated in vitro TNF-alpha, TGF-beta, and IL-6 release of bronchoalveolar lavage cells; however, in stimulated BAL-cell cultures we found a weak but significant correlation between TNF-alpha release and the age (rs = -0.3, P < 0.02). CONCLUSIONS: Impairment of accessory cell function of alveolar macrophages may contribute to an increased risk of pulmonary infection of elderly persons.

Adult↗
PubMed1999

Different cytokine patterns correlate with the extension of disease in pulmonary tuberculosis.

The relative amounts of different pro- and anti-inflammatory cytokines released at the site of infection by bronchoalveolar lavage (BAL) cells may influence the presentation of tuberculosis. To investigate this hypothesis the in situ release by BAL cells of the following cytokines was measured and correlated with the chest X-ray findings of 43 patients with pulmonary tuberculosis: interleukin (IL)-8, macrophage inflammatory protein-1alpha (MIP-1alpha), IL-6, tumor necrosis factor-alpha (TNF-alpha), transforming growth factor-beta (TGF-beta), interferon-gamma (IFN-gamma), IL-2, IL-4 and IL-5. The release of IL-8 and IL-6 decreased with the progression of the disease, while the release of MIP-1alpha was increased in patients with advanced tuberculosis. The release of TNF-alpha and TGF-beta did not differ between patients with or without cavitary lesions. The Th1 (IFN-gamma and IL-2) and Th2 (IL-4 and IL-5) cytokine release exhibited a gradual increment with the advance of tuberculosis. Thus, our data provide evidence that a Th0 cytokine pattern is predominant at the site of pulmonary tuberculosis. In conclusion, immunoparalysis status could not be observed in our patients with severe tuberculosis.

Bronchoalveolar Lavage Fluid↗
PubMed1999

[Diagnosis of chronic berylliosis].

The diagnostic value of the lymphocyte transformation test (BeLT) and the intracutaneous skin test with berylliumsulfate was addressed in 13 patients with chronic berylliosis, and 15 individuals with occupational exposure. Additionally, patients with sarcoidosis (n = 21), tuberculosis (n = 14) and healthy controls (n = 25) were tested with BeLT and yielded negative results. In chronic berylliosis the BeLT was positive in 10/13. In 3/13 the BeLT was negative, but the skin test positive. 6/15 exposed individuals exhibited a positive BeLT. The time course of the skin test differed markedly between the individual berylliosis patients. Typical granulomas were present in 4/10 cases. In 9 exposed individuals BeLT tested negative. Additionally, skin tests were negative in 7 exposed patients, however, unspecific skin reactions were observed in 3 cases. The diagnostic value of Beryllium IT requires further investigation. At present, BeLT appears to be a suitable test to prove beryllium sensitisation.

Adult↗
PubMed1999

Sensitization of tumor cells to ribotoxic stress-induced apoptotic cell death: a new therapeutic strategy.

We describe a procedure that sensitizes chemotherapy-and tumor necrosis factor-resistant human tumor cell populations in vitro and in nude mouse transplants to the immediate triggering of high rates of cell death by anisomycin, an agent causing activation of stress-activated protein kinases [SAPKs, as defined by P. Cohen (Trends Cell Biol., 7: 353-361, 1997)] including p38/RK and c-jun NH2-terminal kinase homologues, following its binding to ribosomal 28S RNA (M. S. Iordanov et al, Mol. Cell. Biol., 17: 3373-3381, 1997). Sensitization is effected by successive application of an inhibitor of histone deacetylation (trichostatin A, butyrate) and of flavopiridol, known as an inhibitor of cyclin dependent kinases and evaluated presently in clinical trials. Effective concentrations of anisomycin, flavopiridol, and trichostatin A are in the submicromolar range. Tumor cell death can be prevented by epidermal growth factor (EGF), if added before flavopiridol or after anisomycin but not if applied between the additions of these agents, suggesting that flavopiridol interrupts an EGF-activated survival pathway and that anisomycin, besides triggering cell death, guards this pathway against the interference by flavopiridol. In contrast to EGF, dibutyryl-cAMP exerts protection that is flavopiridol-insensitive. For triggering cell death, anisomycin cannot be replaced by DNA- or mitotic spindle-targeted drugs in this system. The present findings, that a combination of transcriptional and signal transduction-targeted modulators sensitizes tumor cells synergetically to stress-mediated triggering of cell death and that ribotoxic stress is more efficient in this respect than genotoxic or spindle-targeted stress, bear important implications for the therapeutic exploitation of cellular stress responses. The stepwise sensitization and triggering of cell death in the present system allow separate analysis and manipulation of processes contributing to cellular death susceptibility and of the mechanism responsible for triggering cell death, thus providing the operational basis for further development of this therapeutic approach.

Animals↗
PubMed1998

A new in vitro model for studying human T cell differentiation: T(H1)/T(H2) induction following activation by superantigens.

A new T(H1)/T(H2) in vitro model for mechanistic studies and drug screening in human T cells was established working with ficoll-separated PBMCs or elutriated lymphocytes cultured in serum-free medium. Human T cells could be kept viable and reactive in this medium for several months. In this model, superantigens (SAs) were used to activate exclusively those T cell clones which were known to express specifically SA-binding Vbeta-chains of the T cell receptor. It was possible to identify the activated SA-specific T cells among the whole T cell population by using monoclonal antibodies against these Vbeta-chains and to follow responses involving receptor regulation and cytokine expression. The flow cytometric analysis revealed, that SA exposure caused an upregulation of the IL-2 receptor selectively in the SA-specific subpopulation. Only the T cells of this subpopulation could be shifted towards T(H1) or T(H2) differentiation, which was determined by the distribution of IFN-gamma and IL-4 positive cells. Regulation of IFN-gamma could be detected by flow cytometry after 18 h and that of IL-4 on the third day of cell culture. The differentiation status could be influenced by various measures: T(H1) shifts were achieved in the presence of IL-12 and anti-IL-4, whereas, T(H2) shifts were induced more slowly with monocyte-reduced elutriated lymphocytes in the presence of IL-4, IL-6, anti-IL-12, 1alpha,25-dihydroxy-vitamin-D3 or combinations thereof. It was found that sialidase stimulated whereas TGF-beta and pentoxifylline suppressed both kinds of T cell response. The T(H1)/T(H2) differentiation persisted for several weeks after primary activation if cells were expanded in IL-2 containing serum-free culture medium. Therefore, this human T(H1)/T(H2) in vitro model should be ideal for studying early and late events of infection, allergy, and autoimmunity as well as for investigating the cellular interactions involved. In addition, the early detection of the response pattern makes this model potentially useful for drug screening.

Bacterial Toxins↗
PubMed1998

Soluble intercellular adhesion molecule 1 (sICAM-1) in bronchoalveolar lavage (BAL) cell cultures and in the circulation of patients with tuberculosis, hypersensitivity pneumonitis and sarcoidosis.

Intercellular adhesion molecule-1 (ICAM-1) plays an important role in inflammatory diseases. It is believed that its soluble form (sICAM-1) might be a serum parameter of inflammatory activity with possible relevance in granulomatous disorders. To evaluate this role we measured sICAM-1 by ELISA in serum and shedding of this molecule by BAL cells in patients with granulomatous lung diseases (pulmonary tuberculosis (TB), hypersensitivity pneumonitis (HSP), pulmonary sarcoidosis (PS), and controls). Serum concentrations of sICAM-1 in patients with TB (496.9 +/- 49.7 ng/ml), with HSP (636.5 +/- 85.9.8 ng/ml), and with PS (588.3 +/- 72.2 ng/ml) were significantly increased compared to controls (275.7 +/- 33.1 ng/ml). Spontaneous release of sICAM-1 by BAL cells differed among patient groups (TB: 9.3 +/- 1.7; HSP: 17.5 +/- 1.4; PS: 9.7 +/- 1.5 ng/ml), however, exceeding that of controls significantly (3.8 +/- 0.6 ng/ml). No correlations between the circulating level and the shedding of this molecule by BAL cells were observed within the groups. Significant correlations between serum sICAM-1 and serum tumor necrosis factor alpha (TNFalpha) level were observed in patients with HSP and TB. Kinetic cell culture experiments with BAL cells revealed a dissociation in sICAM-1 shedding and TNFalpha release. After stimulation rapid upregulation of both molecules (5 h) was followed by a cessation of TNFalpha production at 28 h. sICAM-1 shedding, however, was maintained over 2 days. Our results evidence that the circulating pool of sICAM-1, as well as the shedding of this molecule by BAL cells reflect the activity of cells in the inflammatory processes of granulomatous diseases.

Adult↗
PubMed1998

Molecular and immunological characterization of group V allergen isoforms from velvet grass pollen (Holcus lanatus).

Group V grass pollen allergens belong to the major grass pollen allergens causing reactions of type I allergy. cDNAs coding for two isoforms of the group V allergen of velvet grass pollen (Holcus lanatus), a widespread grass species, were isolated from a cDNA library by hybridization with a 5'-terminal reverse-transcribed PCR-derived cDNA probe. Amino acid sequences of the two isoforms, designated rHol l 5.01 and rHol l 5.02, revealed high similarity between them (78% identity) and to group V allergens and their isoforms found in other grass species. Recombinant Hol l 5 isoforms were expressed in Escherichia coli and purified as fusion proteins. To compare their immunological reactivities with group-V-specific monoclonal antibodies and patients' IgE, immunoblotting, ELISA and histamine release assay were performed. Interestingly, monoclonal antibody Bo9, specific for group Vb isoforms of timothy grass, bound only to isoform rHol l 5.01, not to rHol l 5.02. On the other side, IgE reactivities of patients' sera revealed no differences between the two isoforms when investigated by immunoblotting and only slight differences when investigated by ELISA. In histamine release assay both isoforms released comparable amounts of histamine from basophils of four individual patients. Thus, the two group V isoforms of velvet grass pollen exhibit differential binding when tested with monoclonal antibodies, i.e. different structure of single epitopes, but negligible differences concerning overall IgE-binding capacity and histamine-releasing capacity.

Allergens↗
PubMed1998

Comparative study on effects of pentoxifylline, prednisolone and colchicine in experimental alveolitis.

Neutrophil alveolitis is a hallmark of cryptogenic fibrosing alveolitis (CFA), known for its poor prognosis. Corticosteroids, as the remedy of choice, are ineffective in a majority of patients. More and more evidence indicates that pentoxifylline (POF) could be an effective therapeutic alternative. Furthermore, colchicine has been proposed for therapy of CFA for many years now. We conducted an experimental study comparing the efficacy of these drugs in preventing neutrophil alveolitis in vivo. Alveolitis was induced in male rats by intratracheal instillation of bleomycin. Treatment consisted of daily injections of POF i.p., colchicine i.p., or prednisolone i.m. After 8 days the animals were sacrificed and body weights, cell differentials in BAL, amount of proliferating interstitial cells as determined by KI-67 staining of lung tissue, and collagen concentrations in lungs were determined. Bleomycin instillation was followed by a significant weight loss in the animals, a neutrophil alveolitis in BAL and an increased amount of proliferating cells in lung interstitium. POF significantly inhibited any of the parameters named, whereas prednisolone and colchicine had little effect. Data cannot be applied directly in human disease. There are however many similarities between CFA and bleomycin-induced lung injury and alveolitis. We conclude that POF is an effective inhibitor of neutrophil alveolitis, whereas neither colchicine nor prednisolone exerted significant influence in our model. We suggest POF effects should be further investigated regarding anti-inflammatory and anti-fibrotic properties.

Animals↗
PubMed1998

HLA-DQB1 and HLA-DPB1 genotypes in familial sarcoidosis.

Numerous reports on the familial occurrence of sarcoidosis, on regionally different prevalences and on its associations with genetic polymorphisms point to the existence of predisposing genes. We have started to establish a collection of DNA from families with two or more sarcoidosis patients for the purpose of genetic linkage and association studies. In this report we present HLA class II genotypes of affected first-degree relatives from 17 families, including eight instances of affected parent and offspring, six sib pairs, and three sib triplets. Genotyping for HLA-DQB1 revealed an over-representation of DQB1*0603 and DQB1*0604 among alleles shared by affected first degree relatives. The same was found for HLA-DPB1*0201 (Glu69 positive). However, none of the sib triplets had any of these alleles in common.

Family↗
PubMed1998

Post-translational modifications influence IgE reactivity to the major allergen Phl p 1 of timothy grass pollen.

BACKGROUND: Grass group I consists of very potent allergenic components which are found in the pollen of all temperate grasses. Several post-translational modifications are predicted from the cDNA data. OBJECTIVE: The aim of this study was to identify sequential IgE-binding sites on the allergen Phl p 1 and to determine their influence on IgE reactivity. METHODS: Based on cDNA data and microsequencing results we synthesized overlapping decapeptides covering the complete Phl p 1 molecule and tested them for immunological reactivity by means of the PEPSCAN technique. In a dot test we determined the frequency of IgE reactivities to post-translationally modified structures (hydroxylated proline residues, carbohydrate structure, and disulphide formations). RESULTS: Screening by overlapping peptides demonstrated an IgE binding site on the 10 N-terminal amino acids. Comprehensive studies showed that the two hydroxyproline residues of the native Phl p 1 allergen (at positions 5 and 8) and the N-glycan (at position 9) can result in an increased IgE reactivity; 3.3% of the sera exclusively bound to the hydroxyproline bearing peptide, while only 0.4% bound to the proline containing peptide. With regard to glycosylation, we estimated that 20% of sera recognized protein and carbohydrate epitopes, while one serum exclusively bound to the glycan. The formation of disulphide bonds has no detectable effect on the IgE reactivity to Phl p 1. CONCLUSION: Our results indicate that the post-translational modifications, the carbohydrate structure and the hydroxylation of proline residues, can enhance the IgE reactivity of Phl p 1.

Allergens↗
PubMed1998

Differences in the anti-inflammatory effects of theophylline and pentoxifylline: important for the development of asthma therapy?

Antiasthma drugs are now being re-evaluated for their anti-inflammatory effects. Theophylline is an immunomodulator; however, weak effects and the narrow therapeutic window make it a controversial drug. We compared the immunomodulatory potencies of theophylline with those of the xanthines pentoxifylline (POF) and A802715. Using a whole-blood, cell-culture system, we studied the effects on the release of tumor necrosis factor-alpha (TNF-alpha), interferon-gamma (IFN-gamma), and interleukin-6 (IL-6) in six healthy subjects, and, in granulocyte suspensions, the effects on the release of reactive oxygen species (ROS). We also studied the influence of a 14-day treatment with theophylline or POF on the release of the cytokines named above in 14 asthmatics. We found that equimolar concentrations of A802715 most effectively inhibit ROS generation, followed by POF; the effects of theophylline were weakest. A802715-inhibited release of TNF-alpha was four times as potent as that of theophylline, and POF two times as potent. Inhibition of IFN-gamma by A802715 was three times as potent, and by POF two times. Neither drug influenced IL-6 release. After a 14-day treatment of asthmatics, POF proved to inhibit TNF-alpha release more effectively (by 44.3%) than theophylline (7.5%). It is concluded that study of xanthine derivatives in asthmatics might help the development of asthma therapy. POF seems to be an especially promising candidate.

Adult↗
PubMed1998

Serum level of interleukin 8 is elevated in idiopathic pulmonary fibrosis and indicates disease activity.

It has been shown that interleukin 8 (IL-8) is increased in bronchoalveolar lavage fluid (BALF) of patients with idiopathic pulmonary fibrosis (IPF) and there is increasing evidence that it is involved in the pathogenesis of this disease. To date, no data are available as to whether IL-8 is elevated in sera of IPF patients. We obtained sera from 42 patients with IPF and 20 healthy controls at time of BAL. From 20 of 42 patients with IPF and 12 of 20 controls BALF was available, enabling us to measure IL-8 in serum and BALF of the same time point. IL-8 was significantly elevated in serum (54.7 +/- 7.5 pg/ml, p < 0.0001) and BALF (715.7 +/- 112.4 pg/ml, p < 0.0001) of patients with IPF compared with controls (IL-8 in serum, 5.2 +/- 0.8 pg/ml; IL-8 in BALF, 67.3 +/- 9.7 pg/ml). We observed a significant positive correlation between IL-8 levels in BALF and percentage of BALF neutrophils (p < 0.001) and between serum IL-8 and BALF IL-8 levels (p < 0.005) in patients with IPF. Consequently, the serum IL-8 level correlated positively with the percentage of BAL neutrophils (p < 0.01), indicating that it may reflect the degree of neutrophilic alveolitis in IPF. Furthermore, the serum IL-8 level showed a negative correlation with important indicators of impairment of lung function (DL(CO), TLC, VC) and PaO2. In conclusion, we were able to demonstrate that the degree of neutrophilic alveolitis in IPF is reflected by increased serum levels of IL-8 and we suggest that the serological assessment of IL-8 may provide a useful parameter for clinicians in monitoring patients with IPF.

Anti-Inflammatory Agents↗
PubMed1998

Allergenic activity of a major grass pollen allergen is elevated in the presence of nasal secretion.

Phl p5 is a major allergen of timothy grass and causes rhinitis and bronchial asthma in nearly all patients allergic to grass pollen. The biochemical processing of this molecule by the nasal mucosa at its first encounter and possible changes of its biologic activity are unknown. Two isoforms of the allergen were expressed in Escherichia coli and subsequently purified. Conversion of these preparations to various forms with molecular size between 10 and 20 kD in the presence of nasal secretion was observed. Surprisingly, in skin prick test assays with allergic patients the mixture of converted peptides caused significantly higher allergic response when compared with the parent protein. Allergenic activity of the recombinant N-terminal Phl p5a and the C-terminal Phl p5b as measured by skin prick test and histamine release assays was significantly higher than that of the respective parent molecules. Using pancreatic rather than nasal secretion, Phl p5b was completely degraded and its allergenicity was almost completely reduced. Proteolytic degradation converts Phl p5 to defined fragments with increased allergenicity. Complete degradation of Phl p5 on the mucosa could be a preventive strategy to destroy its potency for the induction of an allergic response.

Allergens↗
PubMed1998

[Limits of beryllium detection with laser microprobe mass spectrometry (LAMMS)].

Search for beryllium (Be) in tissues or urine in suspected beryllium disease is often disappointing due to inferior sensitivity of the methods employed. We evaluated the clinical use of laser microprobe mass spectrometry (LAMMS) for measurement of Be and detected the metal to a minimum concentration of 1 microM. We then investigated the biological relevance of this concentration. We looked at the alveolar macrophages in 7 patients subsequent to an incubation period of 24 h as well as peripheral blood mononuclear cells (PBMNC) and various cell lines with and without addition of beryllium sulfate (BeSO4). We also investigated skin biopsies of two patients 28 days after intracutaneous injections of BeSO4 (beryllium skin testing) and alveolar macrophages of A/J mice at various time intervals after a beryllium sensitisation protocol and a single intratracheal injection of BeSO4 (maximum interval: 15 weeks). Be was not defectable in native patient alveolar macrophages (AM), but in 6 of 7 cases after coincubation with BeSO4. There was no significant Be signal in any analysed PBMNC sample or cell line--even after coincubation with Be--or in the skin probes. Murine AM, however, had incorporated significant amounts of Be, which were detectable until the end of the experiments 15 weeks later. We conclude that concentrations of Be in acute disease (here, inoculation of Be in mice) exceed 1 microM and are thus detectable by LAMMS. On the other hand, concentrations in chronic processes (in this cosar, skin testing) are below the detection limits of LAMMS. Further results suggest compartmentalisation of the immune processes induced by Be because the alveolar macrophages were able to incorporate Be while PBMNC were not and because AM--at least in the animal experiments--seem to store Be intracellularly.

Adult↗
PubMed1998

[Spinach powder-induced exogenous allergic alveolitis].

A 51-year old woman developed hypersensitivity pneumonitis to spinach powder, which is used as a food dye. The diagnosis was confirmed by demonstration of IgG2-antibodies in the patient's serum to distinct bands of spinach extract by Western blotting. Furthermore an exposure test with the natural allergen was positive. Severe disease with fever, chills and dyspnoea developed after inhalation of native spinach powder. Arterial pO2 dropped significantly and pulmonary function tests showed severe restrictive impairment and reduction of diffusion capacity. Leucocyte count and the serum concentrations of the cytokines TNF alpha and IL6 and of the soluble IL2-receptor rose significantly in peripheral blood, whereas the concentration of neopterine did not change. 24 hours after exposure bronchoalveolar lavage showed an increase of neutrophils. In lung parenchyma mononuclear interstitial infiltrates and an epitheloid cell granuloma were seen.

Alveolitis, Extrinsic Allergic↗