[Asthma control by utilizing the synergistic effect of inhaled steroids and long-acting beta 2 agonists].
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Adrenal Cortex Hormones↗
Biomedical subjects
M Ehlers
Publications and source records attributed to M Ehlers.
The use of Geographic Information System (GIS) in the frame of the contingency plan implemented during the 1999-2001 avian influenza (AI) epidemic in Italy.
A Geographic Information System (GIS) is a very powerful and flexible software tool for effective management of spatially referenced data (e.g., geodata). Coupling database and GIS technology provides the tools for a detailed analysis of spatial patterns and distributions in veterinary applications. A specific veterinary GIS (VetGIS) toolbox was developed to perform the calculation of indices such as Lorenz curve, GINI index, and a kernel-based animal density estimation. This software was employed for the analysis and management of avian influenza in Italy during the 1999-2000 epidemic.
Animals↗
Excess triiodothyronine as a risk factor of coronary events.
BACKGROUND: Abnormalities in cardiac function, eg, arrhythmias and congestive heart failure, often accompany thyrotoxicosis. A relationship between thyroid hormone excess and the cardiac complications of angina pectoris and myocardial infarction (MI) remains largely speculative. METHODS: The results of thyroid function studies on blood samples drawn from a total of 1049 patients (aged 40 years or older) immediately on emergency medical admission were related to frequencies of angina pectoris and myocardial infarction as determined according to current diagnostic algorithms. After 3 years, those patients who had initially presented with angina pectoris or acute MI were observed for subsequent coronary events; of these (n=185), 98% of the subjects (n=181) could be reevaluated. RESULTS: On hospital admission, the relative rate of angina pectoris and MI was markedly high (odds ratio, 2.6; 95% confidence interval, 1.3-5.2; P=.007) in patients with elevated serum free and total triiodothyronine (T(3)) levels. An initially elevated free T(3) level was a risk factor for subsequent coronary events during the 3-year follow-up (adjusted odds ratio, 4.8; 95% confidence interval, 1.3-17.4; P=.02). CONCLUSIONS: An elevation of serum free T(3) levels at hospital admission is associated with a 2.6-fold greater likelihood of the presence of a coronary event. Moreover, an initially elevated T(3) level is associated with a 3-fold higher risk of developing a subsequent coronary event during the next 3 years. Excess T(3) seemed to be a factor associated with the development and progression of acute myocardial ischemia.
Adult↗
Release of mediators of systemic inflammatory response syndrome in the course of a severe delayed hemolytic transfusion reaction caused by anti-D.
BACKGROUND: In vitro studies suggest that mediators of systemic inflammatory response syndrome are generated in the course of hemolytic transfusion reactions. Evidence for the in vivo significance of these findings is given by the present clinical and laboratory analysis of a severe delayed hemolytic transfusion reaction (DHTR). CASE REPORT: A 67-year-old patient (blood group O, D-negative) with a negative pretransfusion antibody screen received a massive transfusion because of arterial bleeding (Day 1). The transfusion of group O, D-positive red cell concentrates was unavoidable because of limited supplies. At Day 10, the patient developed a DHTR with symptoms of septic-toxic syndrome and signs of hemolysis; he received an exchange transfusion. Serologic markers, as well as proinflammatory and anti-inflammatory mediators, were monitored at the onset of the DHTR and during the exchange transfusion. RESULTS: At Day 10, the direct antiglobulin test was positive; anti-D was present, most likely as the result of an anamnestic immune response. Interleukin (IL)-1 was not detectable; all other mediators monitored were elevated: IL-1 receptor antagonist, tumor necrosis factor, IL-6, IL-8, IL-10, neopterin, elastase, C3a-desArg, C-reactive protein, and fibrinogen. Most of the values declined during the exchange transfusion, which was followed by an improvement of the clinical presentation. CONCLUSIONS: Mediators of systemic inflammatory response syndrome were released in the course of a DHTR caused by anti-D. Severe clinical symptoms could be treated successfully by exchange transfusion.
APACHE↗
Lipopolysaccharide-binding protein is required to combat a murine gram-negative bacterial infection.
An invading pathogen must be held in check by the innate immune system until a specific immune response can be mounted. In the case of Gram-negative bacteria, the principal stimulator of the innate immune system is lipopolysaccharide (LPS), a component of the bacterial outer membrane. In vitro, LPS is bound by lipopolysaccharide-binding protein (LBP) and transferred to CD14--the LPS receptor on the macrophage surface--or to high-density lipoprotein (HDL) particles. Transfer to CD14 triggers an inflammatory response which is crucial for keeping an infection under control. Here we investigate how LBP functions in vivo by using LBP-deficient mice. Surprisingly, we find that LBP is not required in vivo for the clearance of LPS from the circulation, but is essential for the rapid induction of an inflammatory response by small amounts of LPS or Gram-negative bacteria and for survival of an intraperitoneal Salmonella infection.
Acute-Phase Proteins↗
Yeast expression of the cytokine receptor domain of the soluble interleukin-6 receptor.
The complex of the soluble interleukin-6 receptor (sIL-6R) and IL-6 (IL-6) is a potent agonist on cells expressing the signal transducing protein gp 130. In contrast, IL-6 alone only stimulates cells which express a membrane bound form of the IL-6R and gp 130. The natural occurring sIL-6R is generated by shedding of the membrane receptor and to a lesser extend by alternative splicing. We have inserted the coding sequence of the 323 amino acid residues of the human sIL-6R into an expression/secretion vector suitable for the methylotrophic yeast Pichia pastoris. We obtained, however, no detectable expression and secretion of the recombinant protein. When we used only the coding sequence of the cytokine receptor domain of the sIL-6R for the construction of an expression plasmid, this truncated version of the sIL-6R accumulated in the supernatant to 1-5 mg/l. The protein was purified by a single affinity chromatography step using a monoclonal antibody directed against the human IL-6R. Following the same approach, we expressed a truncated splice variant of the sIL-6R. Both, the secreted truncated sIL-6R and the splice variant showed full agonistic biological activity on human hepatoma cells. The described expression strategy will be useful for large scale production of biologically active sIL-6R and might be adapted for the expression of other members of the hematopoietic cytokine receptor family.
Antigens, CD↗
The function of the soluble interleukin 6 (IL-6) receptor in vivo: sensitization of human soluble IL-6 receptor transgenic mice towards IL-6 and prolongation of the plasma half-life of IL-6.
Interleukin 6 (IL-6) is considered an important mediator of acute inflammatory responses. Moreover, IL-6 functions as a differentiation and growth factor of hematopoietic precursor cells, B cells, T cells, keratinocytes, neuronal cells, osteoclasts, and endothelial cells. IL-6 exhibits its action via a receptor complex consisting of a specific IL-6 receptor (IL-6R) and a signal transducing subunit (gp130). Soluble forms of both receptor components are generated by shedding and are found in patients with various diseases such as acquired immune deficiency syndrome, rheumatoid arthritis, and others. The function of the soluble (s)IL-6R in vivo is unknown. Since human (h)IL-6 acts on human and murine target cells, but murine IL-6 on murine cells only, we constructed transgenic mice expressing the hsIL-6R. We report here that in the presence of hsIL-6R, mice are hypersensitized towards hIL-6, mounting an acute phase protein gene induction at significantly lower IL-6 dosages compared to control animals. Furthermore, in hsIL-6R transgenic mice, the detected acute phase response persists for a longer period of time. The IL-6/IL-6R complex prolongs markedly the Il-6 plasma half-life. Our results reinforce the role of the hsIL-6R as an agonistic protein, help to understand the function of the hsIL-6R in vivo, and highlight the significance of the receptor in the induction of the acute phase response.
Acute-Phase Reaction↗
Identification of C to T mutation at position -236 bp in the human NRAMP1 gene promoter.
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Base Sequence↗
Identification of single amino acid residues of human IL-6 involved in receptor binding and signal initiation.
The pleiotropic cytokine interleukin-6 (IL-6) has been predicted to be a protein with four antiparallel alpha-helices. On target cells, IL-6 interacts with a specific ligand binding receptor subunit (IL-6R), and this complex associates with the signal-transducing subunit gp130. Human IL-6 acts on human and murine cells, whereas murine IL-6 is only active on murine cells. The construction of chimeric human/murine IL-6 proteins has allowed us to define a region (residues 77-95, region 2c) within the human IL-6 protein that is important for IL-6R binding and a region (residues 50-55, region 2a2) that is important for IL-6R dependent gp130 interaction. Guided by sequence alignment and molecular modeling, we have constructed several IL-6 variants with point mutations in these regions and have tested them for receptor binding and signal initiation. Within region 2c, phenylalanine 78 was involved in receptor binding, whereas lysine 54 within region 2a2 participated in gp130 activation. Furthermore, some IL-6 variants with lysine 54 replacements could be used to construct muteins that retained receptor binding but failed to activate gp130. Such IL-6 muteins were efficient IL-6 receptor antagonists.
Amino Acid Sequence↗
Residues 77-95 of the human interleuken-6 protein are responsible for receptor binding and residues 41-56 for signal transduction.
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Animals↗
The soluble interleukin-6 receptor.
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Amino Acid Sequence↗
Combining two mutations of human interleukin-6 that affect gp130 activation results in a potent interleukin-6 receptor antagonist on human myeloma cells.
The pleiotropic cytokine interleukin-6 (IL-6) interacts with the specific ligand binding subunit (IL-6R alpha) of the IL-6 receptor, and this complex associates with the signal-transducing subunit gp130 (IL-6R beta). Human IL-6 acts on human and murine cells, whereas murine IL-6 is only active on murine cells. The construction of a set of chimeric human/murine IL-6 proteins has recently allowed us to define a region (residues 43-55) within the human IL-6 protein, which is important for the interaction with gp130. Subdividing this region shows that mainly residues 50-55 of the human IL-6 are necessary for this interaction. Recently, another human IL-6 double mutant (Q159E and T162P) showed reduced affinity to gp130 but residual activity on the human myeloma cell line XG-1. Into this IL-6 mutant we introduced the murine residues 43-49 or 50-55 together with two point mutations, F170L and S176A, which had been reported to increase the affinity of IL-6 to the IL-6R alpha. The resulting IL-6 molecule, which contained the murine residues 50-55, was inactive on human myeloma cells and in addition completely inhibited wild type IL-6 activity on these cells. Such an antagonist may be used as a specific inhibitor of IL-6 activity in vivo.
Animals↗
Functional distinction of two regions of human interleukin 6 important for signal transduction via gp130.
Mutagenesis of a region of human interleukin (IL)-6 which is important for triggering signal transduction via the IL-6 receptor beta-chain (gp130) has lead to the isolation of a variant of human IL-6 (IL-6.Q160E/T163P), which could antagonize the biological activity of wild type IL-6 on the human EBV transformed B cell line CESS and the human hepatoma cell line HepG2. Surprisingly this antagonistic IL-6 variant had an agonistic effect on the human myeloma cell line XG-1, albeit at a 1000-fold higher concentration than wild type IL-6. This residual activity of the mutant arose from triggering gp130, because it could be inhibited by a gp130 specific mAb. Extensive mutagenesis of residues between Q153 and H165 of human IL-6, a region which is partly homologous in cytokines which also signal via gp130 (oncostatin M, ciliary neurotrophic factor, leukaemia inhibitory factor, IL-11), did result in the isolation of a second antagonist for IL-6 activity on CESS and HepG2 cells. However on XG-1 cells this variant was active as well. These results suggest that (an) additional region(s) of the IL-6 molecule might be involved in gp130 triggering. Recently we indeed found that residues Lys42-Ala57 are also important for gp130 triggering. Inhibition experiments with neutralizing IL-6R alpha-chain specific mAb show that this region can be functionally separated from the Q153-H165 region. These findings have important implications for the development of receptor antagonists of IL-6 and IL-6 family members.
Alanine↗
Development of an interleukin (IL) 6 receptor antagonist that inhibits IL-6-dependent growth of human myeloma cells.
The pleiotropic cytokine interleukin 6 (IL-6) plays a role in the pathogenesis of various diseases, such as multiple myeloma, autoimmune and inflammatory diseases and osteoporosis. Therefore, specific inhibitors of IL-6 may have clinical applications. We previously succeeded in developing receptor antagonists of IL-6 that antagonized wild-type IL-6 activity on the human Epstein-Barr virus (EBV)-transformed B cell line CESS and the human hepatoma cell line HepG2. However, these proteins still had agonistic activity on the human myeloma cell line XG-1. We here report the construction of a novel mutant protein of IL-6 in which two different mutations are combined that individually disrupt the association of the IL-6/IL-6 receptor (R) alpha complex with the signaltransducing "beta" chain, gp130, but leave the binding of IL-6 to IL-6R alpha intact. The resulting mutant protein (with substitutions of residues Gln160 to Glu, Thr163 to Pro, and replacement of human residues Lys42-Ala57 with the corresponding residues of mouse IL-6) was inactive on XG-1 cells and weakly antagonized wild-type IL-6 activity on these cells. By introducing two additional substitutions (Phe171Leu, Ser177Arg), the affinity of the mutant protein for IL-6R alpha was increased fivefold, rendering it capable of completely inhibiting wild-type IL-6 activity on XG-1 cells. Moreover, this mutant also antagonized the activity of IL-6, but not that of leukemia inhibitory factor, oncostatin M, or GM-CSF on the human erythroleukemia cell line TF-1, demonstrating its specificity for IL-6. These data demonstrate the feasibility of developing specific IL-6R antagonists. The availability of such antagonists may offer an approach to specifically inhibit IL-6 activity in vivo.
Amino Acid Sequence↗
Identification of two novel regions of human IL-6 responsible for receptor binding and signal transduction.
The pleiotropic cytokine IL-6 has been predicted to be a protein with four antiparallel alpha-helices. Human IL-6 acts on human and murine cells, whereas murine IL-6 is only active on murine cells. The construction of a set of chimeric human/murine IL-6 proteins has recently allowed us to define a new region (residues Lys41-Glu95) within the IL-6 molecule as being important for receptor binding and biologic activity. We subdivided and analyzed this region, which primarily corresponds to the loop between the first and second alpha-helix of IL-6 with respect to its role in the interaction with the ligand binding subunit of the IL-6 receptor complex and with the IL-6 signal-transducing protein gp130. By construction and analysis of human/murine chimeric IL-6 molecules with only 7 to 10 amino acid residues different from human IL-6 we show that two distinct parts of this region are responsible for receptor binding and signal transduction. On the basis of the recently published structure of granulocyte-CSF, we present a three-dimensional model for the tertiary structure of IL-6, which, together with the IL-6 receptor interaction data, allows for the rational design of human IL-6 receptor antagonists.
Base Sequence↗
Distinct patterns of differentiation induced in the monocytic cell line Mono Mac 6.
The human Mono Mac 6 cell line exhibits many characteristics of mature blood monocytes including expression of the CD14 molecule and production of cytokines, such as interleukin-1 (IL-1), IL-6, and tumor necrosis factor. To determine whether these cells can be further differentiated, we treated the cells for up to 3 days with either prostaglandin E2 (PGE2; 10(-5) or 10(-6) M), lipopolysaccharide (LPS; 10-20 ng/ml), or tetradecanoylphorbol-13-acetate (TPA; 10-50 ng/ml). All three reagents reduced proliferation and expression of the early myelomonocytic antigen CD33, and all increased phagocytosis of staphylococci and constitutive expression of mRNA for the macrophage colony-stimulating factor (M-CSF) receptor. By contrast, with respect to CD23 (Fc epsilon RII) expression, CD14 expression, and production of O2-, the three reagents induced distinct responses. Expression of CD23 (Fc epsilon RII) on Mono Mac 6 cells (36%) was not increased by LPS and TPA but was increased by PGE2 treatment to 48%, with a 50% increase of fluorescence intensity. The CD14 antibody My4 stained more than 75% of untreated Mono Mac 6 cells with a specific mean fluorescence intensity of 87.5 channels. This staining was increased more than twofold by both PGE2 and LPS. Staining with the CD14 antibody UCHM1 (6%) was increased to 43% by PGE2 and to 43% by LPS. This increase in CD14 cell surface expression was accompanied by a rise in soluble CD14 and enhancement of CD14 mRNA. By contrast, TPA treatment resulted in a twofold decrease of CD14 cell surface staining with no significant change in sCD14, while CD14 mRNA was transiently down-regulated. Secretion of O2- (stimulated by TPA) was already detectable in untreated Mono Mac 6 cells (6.1 mmol/10(6) cells/30 min), and this response was enhanced 10-fold by pretreatment with LPS but not with PGE2 or TPA. The kinetics of M-CSF receptor mRNA, CD14 expression, and O2- production revealed that these monocytic features started to increase at 6-24 h and were maximal at 2 days. These data suggest that the three reagents induce maturation of the Mono Mac 6 cells to different levels or into different branches of the monocyte system with the notable differences that PGE2 enhances CD23 expression, LPS enhances O2- secretion, and TPA down-regulates CD14.
Antigens, CD↗
Expression of CD14 correlates with lung function impairment in pulmonary sarcoidosis.
CD14 expression on alveolar macrophages (AM) was studied in patients with sarcoidosis using immunocytochemistry and cytometric analysis. Compared with healthy control donors, patients had elevated percentages of CD14-positive AM (22 percent vs 34 percent), and the antigen density was threefold higher (92 vs 297 channels). Furthermore, soluble serum CD14 (ssCD14) was significantly elevated in patients with sarcoidosis with an average of 5.3 +/- 1.6 mg/L vs 3.2 +/- 0.7 mg/L in healthy control subjects. Follow-up of one patient, whose lung function test results improved during therapy with corticosteroids, revealed a concomitant decrease of CD14 staining on AM and of ssCD14. Statistical analysis revealed a negative correlation between CD14 expression on AM and PO2 at rest (p = 0.0005), and after labor (p = 0.02). Levels of ssCD14 gave a positive correlation to reduction of Dco (p = 0.006) and VC (p = 0.05). These data suggest that CD14 expression is related to severity of disease and that it may be useful for monitoring in sarcoidosis.
Adult↗
[Thoracic pain and recurrent cough in right pericardial lung opacity].
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Angiography, Digital Subtraction↗